Refrigeration oil composition

ABSTRACT

The refrigeration oil composition for HFC-based refrigerants or HC-based refrigerants of the invention includes a product of the esterification of an alcohol ingredient including pentaerythritol and dipentaerythritol and a fatty acid ingredient including at least one of a linear or branched fatty acid having 5 carbon atoms and a linear or branched fatty acid having 6 carbon atoms and at least one of a linear or branched fatty acid having 8 carbon atoms and a linear or branched fatty acid having 9 carbon atoms, wherein at least one of the fatty acid having 5 carbon atoms and the fatty acid having 6 carbon atoms in the fatty acid ingredient accounts for 20 to 100% by mol of the total amount of the fatty acid ingredient, and either the alcohol ingredient or the fatty acid ingredient is a mixture.

TECHNICAL FIELD

The present invention relates to a refrigeration oil composition including a polyol ester oil which is soluble with either hydrofluorocarbon-based refrigerants or hydrocarbon-based refrigerants.

BACKGROUND ART

A refrigeration oil composition obtained by dissolving a refrigerant in a refrigeration oil is used as a working fluid in the refrigeration cycle in automotive air conditioners, domestic air conditioners, air conditioning within buildings, cold storehouses, refrigerators, and the like, and hydrofluorocarbon-based refrigerants which contain no chlorine and are constituted of hydrogen, carbon, and fluorine are in use from the standpoint of environmental conservation. Polyol ester oils are used accordingly as refrigeration oils for dissolving the hydrofluorocarbon-based refrigerants therein (see, for example, patent document 1).

However, even refrigeration oil compositions containing the same hydrofluorocarbon-based refrigerant usually differ in requirements concerning the temperature at which the composition separates into the refrigeration oil and the refrigerant (two-layer separation temperature), kinematic viscosity, etc. depending on applications or purposes. Although it is generally necessary to lower the kinematic viscosity of a polyol ester oil for increasing the solubility of a hydrofluorocarbon-based refrigerant therein, the reduced kinematic viscosity results in a decrease in the lubricity of the refrigeration oil composition. Meanwhile, in cases when the lubricity is improved by heightening the kinematic viscosity of the polyol ester oil, the hydrofluorocarbon-based refrigerant comes to separate out.

There are hence cases where a polyol ester oil which is excellent in terms of the solubility of hydrofluorocarbon-based refrigerants therein and a polyol ester oil having excellent lubricity are mixed with each other and used so as to result in solubility and kinematic viscosity that are suitable for the application or purpose (see, for example, patent documents 2 and 3). However, in case where the two polyol ester oils differ considerably in solubility with refrigerants, the polyol ester oil which is less soluble in the refrigerant gradually separates out, depending on the refrigerant used, during the period when the refrigeration oil composition circulates in the refrigeration cycle.

Meanwhile, since hydrofluorocarbon-based refrigerants have an exceedingly high global warming potential, hydrocarbon-based refrigerants, which are considerably low in global warming potential although flammable, are employed in some applications. There is a possibility that such hydrocarbon-based refrigerants might be increasingly used in various applications in future so long as apparatus modification measures are taken to cope with the problem concerning flammability. As refrigeration oils for dissolving hydrocarbon-based refrigerants therein, use has been mainly made of naphthenic or paraffinic mineral oils, alkylbenzene oils, ether oils, fluorinated oils, and the like. However, polyol ester-based lubricating oils having come to be used for the purpose of further improving lubricity. For example, an ester oil which is an ester of a neopentyl polyol including neopentyl glycol or pentaerythritol with a branched monovalent fatty acid having 7 to 9 carbon atoms (see patent document 4) and a polyol ester oil having an alkyl group having 11 to 19 carbon atoms (see patent document 5) are in use.

However, as in the case of hydrofluorocarbon-based refrigerants, such refrigeration oils usually differ in requirements concerning two-layer separation temperature, kinematic viscosity, etc. depending on the applications or purposes of the apparatus to be used. In addition, since hydrocarbon-based refrigerants have an exceedingly low density which is about one-half the density of hydrofluorocarbon-based refrigerants, the volume concentration of a hydrocarbon-based refrigerant dissolved in a refrigeration oil even in the same weight concentration as before is twice and the viscosity, which is influenced by volume concentration, is considerably lower than the conventional refrigerant-solution viscosity. This decrease in refrigerant-solution viscosity is a factor which causes a decrease in lubricity. In the case of using a refrigerant and a refrigeration oil which have high solubility with each other, the refrigeration oil to be used is required to have high kinematic viscosity from the standpoint of heightening the refrigerant-solution viscosity. However, since the refrigerant and the refrigeration oil considerably differ in density and because the refrigeration oil having too high a viscosity has impaired flowability, the refrigerant and the refrigeration oil are less apt to mingle with each other in an actual machine, resulting in a possibility that the refrigeration oil might be supplied in a reduced amount to the surfaces to be lubricated and the lubricity be impaired rather than improved.

However, the refrigeration oil described in patent document 4 has a low viscosity (about 10 to 32 mm²/s at 40° C. according to Examples) and may raise difficulties when used in large refrigerated facilities. Furthermore, the refrigeration oil described in patent document 5 is intended to be used with R290, and is usable only in limited applications.

Meanwhile, in production sites for producing refrigeration oils, it is necessary that many kinds of polyol ester oils produced from a large number of raw materials are ready for use so as to be capable of coping with differences in applications or purposes and in the kinds of hydrofluorocarbon-based refrigerants, and this has resulted in complexation of procurement of raw materials, production management, and product control. The polyol ester oils described in patent documents 2 and 3 also are each intended to be suited for specific refrigerants and specific apparatus, and when used in combination with other refrigerants or in other apparatus, show too high or too low solubility with the refrigerants or have too high or too low viscosity. In particular, it is impossible to obtain suitable solubility with less soluble refrigerants, such as difluoromethane (R-32) refrigerant, while ensuring necessary viscosity.

The same applies to hydrocarbon-based refrigerants. Although it is necessary that many kinds of refrigeration oils produced from a large number of raw materials are ready, the current prior-art techniques including patent documents 4 and 5 are ineffective in overcoming such problems.

PRIOR-ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Patent No. 2787083 -   Patent Document 2: Japanese Patent No. 3510888 -   Patent Document 3: JP-A-2010-235960 -   Patent Document 4: Japanese Patent No. 3909744 -   Patent Document 5: JP-A-2010-31134

SUMMARY OF THE INVENTION Problems that the Invention is to Solve

An object of the invention, which has been achieved in view of the circumstances described above, is to provide a refrigeration oil composition which eliminates the necessity of making many kinds of refrigeration oils or raw materials therefor ready for coping with differences in applications or purposes and in the kinds of refrigerants and which not only is free from separation between oils that have been mixed together, but also is made to have solubility and viscosity that are suitable for any of various hydrofluorocarbon-based refrigerants or hydrocarbon-based refrigerants and for any of various refrigerated facilities, by changing the ratio of specific raw materials.

Means for Solving the Problems

In order to accomplish the object, the present invention provides the following refrigeration oil compositions.

(1) A refrigeration oil composition including a polyol ester oil which is soluble with either a hydrofluorocarbon-based refrigerant or a hydrocarbon-based refrigerant,

wherein the polyol ester oil is a product of the esterification of an alcohol ingredient including pentaerythritol and dipentaerythritol and a fatty acid ingredient including at least one of a linear or branched fatty acid having 5 carbon atoms and a linear or branched fatty acid having 6 carbon atoms and including at least one of a linear or branched fatty acid having 8 carbon atoms and a linear or branched fatty acid having 9 carbon atoms,

at least one of the linear or branched fatty acid having 5 carbon atoms and linear or branched fatty acid having 6 carbon atoms in the fatty acid ingredient accounts for 20 to 100% by mol of the total amount of the fatty acid ingredient, and

either the alcohol ingredient or the fatty acid ingredient is a mixture composed of two components.

(2) The refrigeration oil composition according to (1) above,

wherein at least one of the fatty acids which constitute the fatty acid ingredient is a branched fatty acid.

(3) The refrigeration oil composition according to (1) above,

wherein the fatty acid ingredient is a mixture of: at least one of 2-methylbutanoic acid and 2-methylpentanoic acid; and at least one of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid.

(4) The refrigeration oil composition according to (1) above,

wherein the fatty acid ingredient is a mixture of 2-methylbutanoic acid and 2-ethylhexanoic acid.

(5) The refrigeration oil composition according to any one of (1) to (4) above,

wherein the hydrofluorocarbon-based refrigerant includes at least one member selected from R-32, R-410A, HFO-1234yf, and HFO-1234ze(E).

(6) The refrigeration oil composition according to any one of (1) to (4) above,

wherein the hydrocarbon-based refrigerant including at least one member selected from R-290, R-600a, and R-1270.

(7) The refrigeration oil composition according to any one of (1) to (6) above, having a low-temperature-side two-layer separation temperature and a high-temperature-side two-layer separation temperature, with respect to separation from the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant as measured at an oil content of 20% by weight, of +20 degrees or lower and +35 degrees or higher, respectively. (8) The refrigeration oil composition according to any one of (1) to (7) above, containing at least one of an antioxidant, an epoxy-compound acid scavenger, and an extreme-pressure agent.

Advantage of the Invention

In the refrigeration oil composition of the invention, the polyol ester oil is a product of the esterification of a specific alcohol ingredient and a specific fatty acid ingredient, and has, in the molecule, both a component having excellent solubility with the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant and a component having excellent lubricity. Because of this, the refrigeration oil composition is free from the separation between oils which occurs in the presence of a refrigerant due to a difference therebetween in solubility with the refrigerant, as in the case where a plurality of polyol ester oils are used as a mixture thereof. In addition, the polyol ester oil does not separate from the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant to stagnate in the refrigerating circuit. Since this refrigeration oil is made to have solubility and viscosity that are suitable for any of various hydrofluorocarbon-based refrigerants or hydrocarbon-based refrigerants and for any of various refrigerated facilities, by changing the ratio of specific raw materials, the refrigeration oil composition can satisfactorily and stably exhibit the lubricating performance and cooling performance in refrigerated facilities.

Furthermore, the same alcohols and the same fatty acids can be used in common for constituting the specific alcohol ingredient and the specific fatty acid ingredient, respectively, regardless of the kind of the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant. Consequently, it is not necessary that raw materials for the polyol ester oil are prepared for each refrigerant, as in conventional techniques, and the complexity of procurement of raw materials and production management can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is graphs which show the results of examinations for a relationship between open time and moisture content in oil, with respect to Example 2A and Comparative Example 1A.

FIG. 2 is graphs which show the results of examinations for a relationship between open time and moisture content in oil, with respect to Example 2B and Comparative Example 1B.

MODES FOR CARRYING OUT THE INVENTION

The refrigeration oil composition of the invention includes a polyol ester oil. As the polyol ester oil, use is made of a product of the esterification of an alcohol ingredient including pentaerythritol and dipentaerythritol and a fatty acid ingredient including at least one of a linear or branched fatty acid having 5 carbon atoms and a linear or branched fatty acid having 6 carbon atoms and including at least one of a linear or branched fatty acid having 8 carbon atoms and a linear or branched fatty acid having 9 carbon atoms. It is, however, noted that either the alcohol ingredient or the fatty acid ingredient is a mixture composed of two components. Meanwhile, since a fatty acid can be present as a racemate, a substance which is one fatty acid but is a racemate is regarded as two kinds of fatty acids. This polyol ester oil can be synthesized so as to be applicable to any of various hydrofluorocarbon refrigerants or hydrocarbon-based refrigerants which differ in solubility and to any of various refrigerated facilities which differ in required kinematic viscosity, by merely changing the ratio of components with respect to a specific combination of components of the alcohol ingredient and fatty acid ingredient as raw materials.

Pentaerythritol and dipentaerythritol, which are used as the alcohol ingredient, give an esterification product that not only has lubricity but also is less apt to undergo influences of moisture, the susceptibility to which is a drawback of ester compounds, and has exceedingly high hydrolytic resistance. Furthermore, the solubility with the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant and the affinity for metal surfaces can be regulated by selecting the kinds of the fatty acids to be used for the esterification. Since dipentaerythritol is a dimer of pentaerythritol, a combination thereof with pentaerythritol brings about excellent stability. By regulating the proportion of the pentaerythritol to the dipentaerythritol, the viscosity of the lubricating oil can be set to a value required by a refrigerated facility. Furthermore, by regulating the high-temperature-side two-layer separation temperature to a more suitable value, lubricity within the compressor can be ensured.

The fatty acid ingredient is configured of at least one of a linear or branched fatty acid having 5 carbon atoms (hereinafter inclusively referred to as “pentanoic acid”) and a linear or branched fatty acid having 6 carbon atoms (hereinafter inclusively referred to as “hexanoic acid”) and containing a linear or branched fatty acid having 8 carbon atoms (hereinafter inclusively referred to as “octanoic acid”) and a linear or branched fatty acid having 9 carbon atoms (hereinafter inclusively referred to as “nonanoic acid”).

At least one of the pentanoic acid and hexanoic acid is a fatty acid ingredient for improving solubility with the refrigerant. Although a fatty acid ingredient having a smaller number of carbon atoms is more effective in improving solubility, use is made of the fatty acid(s) having 5 or 6 carbon atoms in order to ensure hydrolytic stability and viscosity to some degree. From the standpoint of ensuring the solubility of the polyol ester oil with refrigerant R-32, which is especially poorly soluble, the upper limit of the length of the carbon chain in this ingredient is 5 in terms of the number of carbon atoms; normal pentanoic acid is applicable but normal hexanoic acid is undesirable. This fatty acid serves also as an ingredient for regulating viscosity and ensuring lubricity, and heightens the polarity of the molecule to thereby reduce solubility and improve the affinity for metal surfaces.

At least one of the octanoic acid and nonanoic acid is a fatty acid ingredient for ensuring viscosity and lubricity and for improving solubility with the refrigerant. A fatty acid ingredient having a larger number of carbon atoms is more effective in improving viscosity and has reduced polarity to improve solubility. However, in view of a decrease in solubility and from the standpoint of ensuring low-temperature flowability and oxidative stability, use is made of the fatty acid(s) having 8 or 9 carbon atoms, which has been actually used for conventional refrigeration oils.

Especially from the standpoints of reducing adverse influences on solubility and improving hydrolytic stability and viscosity, the branched fatty acids are more preferred. Consequently, the branched form of each acid is more effective than the linear form thereof in enhancing the solubility of the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant and is capable of further lowering the low-temperature-side two-layer separation temperature. Furthermore, since the branched form is more effective in heightening viscosity than the linear form, use of the branched form facilitates the setting of viscosity to that required by a refrigerated facility. In addition, the branched form is capable of more improving hydrolytic stability than the linear form. Consequently, a combination of fatty acid components which constitute the fatty acid ingredient and in which at least one is the branched form is preferred to a combination in which all the fatty acids are linear. Most preferred of such combinations is one in which all the fatty acids are branched.

The branched chains of the fatty acids preferably are methyl group or ethyl group, and it is preferable that the number of branches in each branched fatty acid is 1 to 3. Furthermore, a preferred branching position is the 2-position, i.e., the position adjacent to the carboxyl group. Preferred of such branched fatty acids are 2-methylbutanoic acid as a branched pentanoic acid, 2-methylpentanoic acid as a branched hexanoic acid, 2-ethylhexanoic acid as a branched octanoic acid, and 3,5,5-trimethylhexanoic acid as a branched nonanoic acid. Consequently, preferred as the fatty acid ingredient are mixtures of: at least one of 2-methylbutanoic acid and 2-methylpentanoic acid; and at least one of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid. Especially preferred is a mixture of 2-methylbutanoic acid and 2-ethylhexanoic acid.

In the invention, the kinematic viscosity of the polyol ester oil is 15 to 350 mm²/s (40° C.), and is suitably selected in accordance with the apparatus in which the refrigeration oil composition is to be used and with applications. Especially for air conditioners, it is preferable that the kinematic viscosity of the polyol ester oil is 46 to 100 mm²/s (40° C.). Kinematic viscosities thereof less than 46 mm²/s (40° C.) result in poor lubricity, while kinematic viscosities thereof exceeding 100 mm²/s (40° C.) result in too high viscosity resistance and a considerable decrease in performance. A more preferred range of the kinematic viscosity thereof is 50 to 80 mm²/s (40° C.). For small refrigerated facilities, it is preferable that the kinematic viscosity of the polyol ester oil is 22 to 68 mm²/s (40° C.). Kinematic viscosities thereof less than 22 mm²/s (40° C.) result in poor lubricity, while kinematic viscosities thereof exceeding 68 mm²/s (40° C.) result in too high viscosity resistance and a considerable decrease in performance. A more preferred range of the kinematic viscosity thereof is 30 to 50 mm²/s (40° C.). For large refrigerated facilities, it is preferable that the kinematic viscosity of the polyol ester oil is 68 to 320 mm²/s (40° C.). Kinematic viscosities thereof less than 68 mm²/s (40° C.) result in poor lubricity or poor compression chamber-sealing properties, while kinematic viscosities thereof exceeding 320 mm²/s (40° C.) result in too high viscosity resistance and a considerable decrease in performance. Since refrigerated facilities differ markedly in required kinematic viscosity depending on the compressor and refrigeration system, it is necessary that the polyol ester oil is regulated so as to have the kinematic viscosity required by a refrigerated facility. Such a kinematic viscosity may be attained by regulating the proportion in which pentaerythritol and dipentaerythritol are mixed together; pentaerythritol is used in an amount of 10 to 90% by mol based on the whole alcohol ingredient, with the remainder being dipentaerythritol. In the case where it is necessary that a plurality of polyol ester oils which each are the polyol ester oil of the invention and which differ in kinematic viscosity are mixed with each other, the resultant mixture can be used without suffering separation between the oils so long as the solubility of each polyol ester oil with the refrigerant to be used is appropriate. Especially for air conditioners, it is preferred to employ such a proportion that the amount of pentaerythritol is 40 to 80% by mol based on the whole alcohol ingredient, with the remainder being dipentaerythritol. For small refrigerated facilities, it is preferred to employ such a proportion that the amount of pentaerythritol is 60 to 90% by mol based on the whole alcohol ingredient, with the remainder being dipentaerythritol. For large refrigerated facilities, it is preferred to employ such a proportion that the amount of pentaerythritol is 10 to 40% by mol based on the whole alcohol ingredient, with the remainder being dipentaerythritol.

Meanwhile, the hydrofluorocarbon-based refrigerant to be dissolved in the refrigeration oil composition is not particularly limited, and one which has conventionally been used as a refrigerant can be used, such as, for example, R-134a (tetrafluoroethane) or R-410A (a mixture of difluoromethane and pentafluoroethane). It is, however, noted that requirements for environmental conservation are becoming severer and, especially in Europe, it was decided to use HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) as a new refrigerant in the automotive air conditioners of motor vehicles manufactured in and after the year 2011 (2nd International Workshop on Mobile Air Conditioning and Auxiliary Systems-Trono, Italy Nov. 29, 2007 and European Automotive A/C Convention, Sep. 22-23, 2008). Besides that refrigerant, the following are receiving attention as next-generation refrigerants: HFO-1234ze(E) (trans-1,3,3,3-tetrafluoro-1-propene), R-32 (difluoromethane), a mixture of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) and R-32 (difluoromethane), and a mixture of HFO-1234ze(E) (trans-1,3,3,3-tetrafluoro-1-propene) and R-32 (difluoromethane). In the invention also, it is preferred to use HFO-1234yf, HFO-1234ze(E), or R-32 as the hydrofluorocarbon-based refrigerant. Any one of these refrigerants and R-410A, which is a refrigerant used hitherto, may be used alone, or two or more thereof may be used as a mixture thereof. In particular, R-32 is receiving attention as a next-generation refrigerant since R-32 has a low global warming potential (GWP), is not a mixed refrigerant, and is relatively inexpensive. However, this refrigerant has low solubility with conventional polyol ester oils and are prone to cause two-layer separation. According to the invention, however, by regulating the components of the alcohol ingredient and of the fatty acid ingredient and regulating the mixing proportions thereof, a refrigeration oil composition which is prevented from undergoing two-layer separation and has satisfactory lubricity is obtained even when R-32 is used.

The hydrocarbon-based refrigerant also is not limited, and use can be made of any one of hydrocarbon-based refrigerants which have hitherto been used in some appliances, such as, for example, R-600a, R-290 (propane), and R-1270 (propylene), or a mixture of two or more thereof. In particular, R-290 is receiving attention as a next-generation refrigerant since R-290 has a low global warming potential (GWP), is not a mixed refrigerant, and is relatively inexpensive. However, this refrigerant has too high solubility with conventional naphthenic mineral oils to cause a decrease in viscosity due to the diluting effect of the refrigerant and is hence prone to cause a decrease in lubricity. According to the invention, however, by regulating the components of the alcohol ingredient and of the fatty acid ingredient and regulating the mixing proportions thereof, a refrigeration oil composition having satisfactory lubricity is obtained using R-290.

In order to produce the refrigeration oil composition of the invention, a hydrofluorocarbon-based refrigerant or a hydrocarbon-based refrigerant is selected first. Thereafter, the mixing proportion of pentaerythritol to dipentaerythritol, the mixing proportion of at least one of pentanoic acid and hexanoic acid to at least one of octanoic acid and nonanoic acid, and the mixing proportion of the alcohol ingredient to the fatty acid ingredient are set while taking account of solubility with the selected refrigerant and lubricity, and the alcohol ingredient is subjected to esterification reaction with the fatty acid ingredient to produce a polyol ester oil.

In the refrigeration oil composition, it is preferable that with respect to separation from the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant, the high-temperature-side two-layer separation temperature is +35° C. or higher, in particular, in the range of +40 to +65° C., and the low-temperature-side two-layer separation temperature is +20° C. or lower, in particular, 0° C. or lower. For use in refrigerated facilities or large air conditioners, there is a request for −30° C. or lower, or for −50° C. or lower. Such solubility can be obtained by regulating the mixing proportion of at least one of the pentanoic acid and hexanoic acid to at least one of the octanoic acid and nonanoic acid in the fatty acid ingredient.

Specifically, the amount of at least one of pentanoic acid and hexanoic acid is regulated to 20 to 100% by mol based on the whole fatty acid ingredient, with the remainder being at least one of octanoic acid and nonanoic acid. Especially for domestic air conditioners in which R-32 is used, a preferred proportion is one in which 2-methylbutanoic acid is used in an amount of 40 to 60% by mol, with the remainder being 2-ethylhexanoic acid.

In case where the high-temperature-side two-layer separation temperature is not +35° C. or higher and the low-temperature-side two-layer separation temperature is not +20° C. or lower, the solubility between the polyol ester oil and the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant is insufficient and separation between the two occurs in high-temperature parts of the refrigeration cycle, e.g., the condenser, and in low-temperature parts thereof, e.g., the evaporator. Once the separation occurs, the following adverse influences are exerted thereby: the polyol ester oil stagnates in heat exchangers, such as the condenser and the evaporator, to inhibit heat exchange; the amount of the polyol ester oil which returns to the compressor decreases to cause compressor troubles due to insufficient lubrication; and the separation inhibits refrigerant circulation to thereby considerably lower the cooling performance. Incidentally, any polyol ester oil produced from one alcohol and one fatty acid is prone to crystallize or solidify at room temperature to low temperatures and hence cannot be adopted. In addition, it is noted that in cases when a fatty acid which is apparently constituted of one component but is a racemate is employed, this fatty acid is regarded as being constituted of two components. Consequently, 2-methylbutanoic acid, which is a pentanoic acid, is more effective in preventing crystallization than 3-methylbutanoic acid, which also is a pentanoic acid, and 2-methylpentanoic acid, which is a hexanoic acid, is more effective in preventing crystallization, than 2-ethylbutanoic acid, which also is a hexanoic acid.

In particular, for refrigerated facilities or large air conditioners in which R-32 is used, a preferred proportion is one in which 2-methylbutanoic acid is used in an amount of 60 to 90% by mol, with the remainder being 2-ethylhxanoic acid. For refrigerated facilities in which HFO-1234ze(E) is used, preferred are a proportion in which 2-methylbutanoic acid is used in an amount of 20 to 60% by mol, with the remainder being 2-ethylhexanoic acid, and a proportion in which 2-methylpentanoic acid is used in an amount of 20 to 60% by mol, with the remainder being 3,5,5-trimethylhexanoic acid.

There are no limitations on the esterification reaction, and the reaction can be conducted in accordance with methods in practical use. In the esterification reaction, the carboxyl groups of the fatty acids react with all the hydroxyl groups of the alcohols. Consequently, once the mixing proportion of pentaerythritol to dipentaerythritol in the alcohol ingredient is decided, the total amount of hydroxyl groups in the mixture is also determined and, hence, the amount of the fatty acid ingredient to be used may be set in accordance with the total amount of hydroxyl groups.

Processes for producing the refrigeration oil composition are specifically shown below. For example, in the case where HFO-1234ze(E) has been selected as a hydrofluorocarbon-based refrigerant for small refrigerated facilities and where the required kinematic viscosity at 40° C. is 15 to 60 mm²/s, then an alcohol ingredient in which pentaerythritol accounts for 60 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 20 to 90% by mol thereof, with the remainder being at least one of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid, are used and esterified to produce a polyol ester oil. Thereafter, HFO-1234ze(E) is dissolved in this polyol ester oil to obtain a refrigeration oil composition. The refrigeration oil composition thus obtained satisfies the high-temperature-side two-layer separation temperature, low-temperature-side two-layer separation temperature, and kinematic viscosity described above and is excellent in terms of refrigerating performance and lubricating performance.

Meanwhile, in the case where, for example, HFO-1234ze(E) has been selected for large refrigerated facilities and where the required kinematic viscosity at 40° C. is 90 to 240 mm²/s, then use is made of either a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 0 to 70% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which at least one of 2-methylbutanoic acid and 2-methylpentanoic acid accounts for 20 to 60% by mol thereof, with the remainder being 2-ethylhexanoic acid, or a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which at least one of 2-methylbutanoic acid and 2-methylpentanoic acid accounts for 20 to 60% by mol thereof, with the remainder being 3,5,5-trimethylhexanoic acid. HFO-1234ze(E) is dissolved in this polyol ester oil to obtain a refrigeration oil composition.

Furthermore, in the case where, for example, R-32 has been selected for domestic air conditioners and where the required kinematic viscosity at 40° C. is 40 to 80 mm²/s, then use is made of either a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 40 to 70% by mol thereof, with the remainder being 2-ethylhexanoic acid, or a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 50 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 30 to 70% by mol thereof, with the remainder being 3,5,5-trimethylhexanoic acid. R-32 is dissolved in this polyol ester oil to obtain a refrigeration oil composition.

Moreover, also in the case of a conventional mode in which R-410A is selected for domestic air conditioners, use can be made of a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 40 to 70% by mol thereof, with the remainder being 2-ethylhexanoic acid. R-410A is dissolved in this polyol ester oil to obtain a refrigeration oil composition.

Furthermore, also in the case of a conventional mode in which R-410A is selected for large air conditioners, use can be made of a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 40 to 60% by mol thereof, with the remainder being 2-ethylhexanoic acid. R-410A is dissolved in this polyol ester oil to obtain a refrigeration oil composition.

Moreover, also in the case where R-32, which is a next-generation refrigerant, and R-410A, which is a conventional refrigerant, mingle with each other in a large air conditioner because of, for example, the configuration of the facilities, use can be made of a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 40 to 60% by mol thereof, with the remainder being 2-ethylhexanoic acid. A mixed refrigerant composed of R-32 and R-410A is dissolved in this polyol ester oil to obtain a refrigeration oil composition.

Furthermore, in the case where a mixed refrigerant composed of R-32 and either HFO-1234yf or HFO-1234ze(E) has been selected for domestic air conditioners and where the required kinematic viscosity at 40° C. is 40 to 80 mm²/s, then use is made of either a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 20 to 50% by mol thereof, with the remainder being 2-ethylhexanoic acid, or a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 50 to 100% by mole thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 30 to 70% by mol thereof, with the remainder being 3,5,5-trimethylhexanoic acid. A mixed refrigerant composed of R-32 and either HFO-1234yf or HFO-1234ze(E) is dissolved in the polyol ester oil to obtain a refrigeration oil composition.

Furthermore, in the case where R-290 has been selected as a hydrocarbon-based refrigerant for small refrigerated facilities and where the required kinematic viscosity at 40° C. is 15 to 60 mm²/s, then an alcohol ingredient in which pentaerythritol accounts for 60 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 20 to 90% by mol thereof, with the remainder being at least one of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid, are used and esterified to produce a polyol ester oil. Such a refrigeration oil composition satisfies the high-temperature-side two-layer separation temperature, low-temperature-side two-layer separation temperature, and kinematic viscosity described above and is excellent in terms of refrigerating performance and lubricating performance.

Furthermore, in the case where, for example, R-1270 has been selected for large refrigerated facilities and where the required kinematic viscosity at 40° C. is 90 to 240 mm²/s, then use is made of either a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 0 to 70% by mole thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which at least one of 2-methylbutanoic acid and 2-methylpentanoic acid accounts for 20 to 60% by mol thereof, with the remainder being 2-ethylhexanoic acid, or a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which at least one of 2-methylbutanoic acid and 2-methylpentanoic acid accounts for 20 to 60% by mol thereof, with the remainder being 3,5,5-trimethylhexanoic acid.

Furthermore, in the case where, for example, R-290 has been selected for domestic air conditioners and where the required kinematic viscosity at 40° C. is 40 to 80 mm²/s, then use is made of either a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 40 to 70% by mol thereof, with the remainder being 2-ethylhexanoic acid, or a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 50 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 30 to 70% by mol thereof, with the remainder being 3,5,5-trimethylhexanoic acid.

Furthermore, in the case where, for example, a mixed refrigerant composed of R-290 and R-1270 has been selected for domestic air conditioners and where the required kinematic viscosity at 40° C. is 40 to 80 mm²/s, then use is made of either a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 40 to 80% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 20 to 50% by mol thereof, with the remainder being 2-ethylhexanoic acid, or a polyol ester oil obtained by esterifying an alcohol ingredient in which pentaerythritol accounts for 50 to 100% by mol thereof, with the remainder being dipentaerythritol, and a fatty acid ingredient in which 2-methylbutanoic acid accounts for 30-70% by mol thereof, with the remainder being 3,5,5-trimethylhexanoic acid.

As described above, by using pentaerythritol, dipentaerythritol, at least one of pentanoic acid and hexanoic acid, and at least one of octanoic acid and nonanoic acid in common and by merely changing the mixing proportions thereof, polyol ester oils which are usable with various hydrofluorocarbon-based refrigerants or hydrocarbon-based refrigerants are obtained. Consequently, to prepare pentaerythritol, dipentaerythritol, at least one of pentanoic acid and hexanoic acid, and at least one of octanoic acid and nonanoic acid beforehand suffices for the production site, and the complexation of raw material procurement and of production management can be significantly reduced as compared with the case where many kinds of polyol ester oils are prepared.

Various additives can be added to the refrigeration oil composition of the invention. The polyol ester oil has the possibility of undergoing oxidative deterioration or hydrolysis due to the outside air or moisture which has infiltrated into the refrigeration cycle or due to the influence of residues, e.g., a rust preventive, which remain in the refrigeration cycle, resulting in a possibility that an acidic component might be produced by the deterioration or hydrolysis to corrode the inside of the system. Furthermore, refrigerants having a double bond in the molecule, such as HFO-1234yf, HFO-1234ze(E), and R-1270, are more prone, than other hydrofluorocarbon-based refrigerants, to undergo oxidative deterioration or hydrolysis due to heat or the outside air or moisture which has infiltrated into the refrigeration cycle or due to the influence of residues, e.g., a rust preventive, which remain in the refrigeration cycle, resulting in a possibility that an acidic component might be produced by the deterioration or hydrolysis to corrode the inside of the system. It is therefore preferred to add an epoxy-compound acid scavenger. In particular, epoxy-compound acid scavengers such as glycidyl ethers and glycidyl esters are preferred since such compounds have a high acid-scavenging effect. Furthermore, it is preferred to use an epoxy-compound acid scavenger having an epoxycycloalkyl group or an epoxy-compound acid scavenger obtained by introducing a glycidyl group into an end of polypropylene glycol, from the standpoint of affinity for the polyol ester oil and hydrofluorocarbon-based refrigerant. Moreover, an epoxy-compound acid scavenger obtained by introducing a glycidyl group into an alcohol or fatty acid having 10 or less carbon atoms is preferred since this compound shows improved acid-scavenging ability due to the high dispersibility thereof in the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant.

By adding a lubricity improver, such as an extreme-pressure agent or an oiliness agent, not only the metallic surfaces of sliding portions can be prevented from wearing or seizing but also the lubricity is enhanced to reduce frictional heating, making it possible to inhibit the decomposition of refrigerants having a double bond in the molecule, such as HFO-1234yf, HFO-1234ze(E), and R-1270. As the extreme-pressure agent, use may be made of a phosphoric acid type extreme-pressure agent or a thiophosphoric acid type extreme-pressure agent in accordance with requirements of the refrigerated facility or air conditioner. Since thiophosphoric acid type extreme-pressure agents cause precipitation of a sulfur compound depending on the conditions and it is hence necessary to minimize the amount thereof if these agents are added, phosphoric acid type extreme-pressure agents are preferred. Examples of the phosphoric acid type extreme-pressure agents include tricresyl phosphate, triphenyl phosphate, tris(tert-butylphenyl)phosphate, monophenyl bis(tert-butylphenyl)phosphate, and diphenyl tert-butylphenyl phosphate. As the oiliness agent, use may be made of one which has no active element, e.g., phosphorus or sulfur, and which utilizes the affinity of oxygen for metals, such as a long-chain-alkyl alcohol, alkyl monoglyceride, or fatty acid methyl ester. Examples thereof include oleyl alcohol, isostearyl alcohol, oleyl monoglyceride, linolenyl monoglyceride, and methyl oleate.

It is also preferred to add an antioxidant in order to inhibit refrigerants having a double bond in the molecule, such as HFO-1234yf, HFO-1234ze(E), and R-1270, from decomposing or from undergoing oxidative deterioration due to the infiltration of outside air into the refrigeration cycle. Examples of the antioxidant include phenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, and 2,2′-methylenebis(4-methyl-6-tert-butylphenol) and amine-compound antioxidants such as phenyl-α-naphthylamine and N,N′-diphenyl-p-phenylenediamine. However, since the amine-compound antioxidants have reactivity with refrigerants having a double bond in the molecule, such as HFO-1234yf, HFO-1234ze(E), and R-1270, it is preferred to use these antioxidants in the refrigeration oil to be applied to other hydrofluorocarbon-based refrigerants or to hydrocarbon-based refrigerants.

Any one of the epoxy-compound acid scavenger, lubricity improver, and antioxidant may be used alone, or the three agents can be used in combination. There are no limitations on the amount of each agent to be added, so long as the effect thereof is produced. It is, however, preferable that the amounts of the epoxy-compound acid scavenger, lubricity improver, and antioxidant are 0.25 to 2% by mass, 0.5 to 4% by mass, and 0.1 to 1% by mass, respectively, based on the whole refrigeration oil composition. In case where the addition amount of each agent is less than the lower limit, the effect thereof cannot be sufficiently produced. Even when the amount of each agent is larger than the upper limit, not only the effect is not enhanced any more, but also the relative content of the polyol ester oil is low, resulting in poor lubricity.

In addition to those additives, additives in general use may be added for the purpose of improving performances other than those mentioned above.

EXAMPLES

Test Examples are shown below to further explain the invention, but the invention should not be construed as being limited by the following Examples in any way. Incidentally, Test A relates to refrigeration oil compositions for hydrofluorocarbon-based refrigerants, while Test B relates to refrigeration oil compositions for hydrocarbon-based refrigerants.

<Test A: Refrigeration Oil Compositions for Hydrofluorocarbon-Based Refrigerants>

The alcohol ingredients and fatty acid ingredients shown in Table A were esterified to produce polyol ester oils. In the table, PE represents pentaerythritol, DiPE represents dipentaerythritol, LPt represents normal pentanoic acid (a pentanoic acid), 2 MBu represents DL-2-methylbutanoic acid (a pentanoic acid), LHx represents normal hexanoic acid (a hexanoic acid), 2 MPt represents DL-2-methylpentanoic acid (a hexanoic acid), 2EBu represents 2-ethylbutanoic acid (a hexanoic acid), 2EHx represents a 2-ethylhexanoic acid (an octanoic acid), and TMHx represents 3,5,5-trimethylhexanoic acid (a nonanoic acid), and the mixing proportion of each alcohol ingredient to the fatty acid ingredient is in molar ratio. A poly(vinyl ether) oil (comparative oil 15A) which is currently in use as a refrigeration oil was added as a comparative oil besides ester oils produced from the alcohol ingredient and fatty acid ingredient. Furthermore, comparative oils 18A, 19A, and 20A were added as mixed oils. The refrigeration oil A used in the mixed oils is in use as a refrigeration oil for HFC refrigerators; this refrigeration oil is highly soluble with refrigerant R-32 but has too low viscosity to be used as such in the refrigerated facilities or air conditioners to which the invention is intended to be applied.

TABLE A (Polyol ester oils used in Examples and Comparative Examples) Alcohol ingredient Fatty acid ingredient Oil No. PE DiPE Acid 1 Acid 2 Synthetic oil 1A 0.60 0.40 2MBu: 0.4 2EHx: 0.6 Synthetic oil 2A 0.55 0.45 2MBu: 0.5 2EHx: 0.5 Synthetic oil 3A 0.55 0.45 2MBu: 0.7 2EHx: 0.3 Synthetic oil 4A 0.55 0.45 2MBu: 0.85 2EHx: 0.15 Synthetic oil 5A 0.30 0.70 2MBu: 0.5 2EHx: 0.5 Synthetic oil 6A 0.55 0.45 2MBu: 0.45 2EHx: 0.55 Synthetic oil 7A 1.0 0.0 2MBu: 0.5 TMHx: 0.5 Synthetic oil 8A 0.50 0.50 2MBu: 1.0 TMHx: 0.0 Synthetic oil 9A 1.0 0.0 2MBu: 0.4 TMHx: 0.6 Synthetic oil 10A 0.85 0.15 2MBu: 0.6 TMHx: 0.4 Synthetic oil 11A 0.0 1.0 LPt: 0.8 TMHx: 0.2 Synthetic oil 12A 0.25 0.75 2MPt: 0.8 2EHx: 0.2 Synthetic oil 13A 0.25 0.75 2MPt: 1.0 — Synthetic oil 14A 1.0 0.0 2MPt: 0.5 TMHx: 0.5 Synthetic oil 15A 1.0 0.0 2EBu: 0.75 TMHx: 0.25 Synthetic oil 16A 0.0 1.0 2MBu: 0.5 2EHx: 0.5 Synthetic oil 17A 0.0 1.0 2MBu: 0.65 2EHx: 0.35 Synthetic oil 18A 0.0 1.0 2MBu: 1.0 — Synthetic oil 19A 0.10 0.90 2MBu: 1.0 — Synthetic oil 20A 0.70 0.30 2MBu: 0.5 TMHx: 0.5 Synthetic oil 21A 0.50 0.50 2MBu: 0.5 TMHx: 0.5 Synthetic oil 22A 0.30 0.70 2MBu: 0.5 TMHx: 0.5 Synthetic oil 23A 0.0 1.0 2MBu: 0.9 TMHx: 0.1 Synthetic oil 24A 0.0 1.0 2MBu: 0.65 TMHx: 0.35 Synthetic oil 25A 0.0 1.0 2MBu: 0.5 TMHx: 0.5 Synthetic oil 26A 1.0 0.0 LPt: 0.5 2EHx: 0.5 Synthetic oil 27A 1.0 0.0 LPt: 0.75 TMHx: 0.25 Synthetic oil 28A 1.0 0.0 LPt: 0.5 TMHx: 0.5 Synthetic oil 29A 1.0 0.0 2MBu: 1.0 — Synthetic oil 30A 1.0 0.0 2MBu: 0.75 2EHx: 0.25 Synthetic oil 31A 1.0 0.0 2MBu: 0.5 2EHx: 0.5 Synthetic oil 32A 0.70 0.30 2MBu: 0.85 2EHx: 0.15 Synthetic oil 33A 1.0 0.0 2MBu: 0.75 TMHx: 0.25 Synthetic oil 34A 1.0 0.0 2MPt: 1.0 — Synthetic oil 35A 1.0 0.0 2MPt: 0.75 2EHx: 0.25 Comparative oil 1A 1.0 0.0 2EHx: 0.5 TMHx: 0.5 Comparative oil 2A 1.0 0.0 LHx: 0.25 TMHx: 0.75 Comparative oil 3A 0.0 1.0 LHx: 0.65 TMHx: 0.35 Comparative oil 4A 0.0 1.0 LHx: 1.0 — Comparative oil 5A 1.0 0.0 2EBu: 1.0 — Comparative oil 6A 0.65 0.35 2EHx: 1.0 — Comparative oil 7A 0.0 1.0 LHx: 0.35 TMHx: 0.65 Comparative oil 8A 1.0 0.0 TMHx: 1.0 — Comparative oil 9A 0.0 1.0 2EHx: 0.5 TMHx: 0.5 Comparative oil 10A 0.0 1.0 2MPt: 0.35 2EHx: 0.65 Comparative oil 11A 1.0 0.0 2EHx: 1.0 — Comparative oil 12A 1.0 0.0 LPt: 0.25 2EHx: 0.75 Comparative oil 13A 1.0 0.0 LHx: 0.5 TMHx: 0.5 Comparative oil 14A 1.0 0.0 2MPt: 0.25 2EHx: 0.75 Comparative oil 15A refrigerant R-410A/ether oil for air conditioner Comparative oil 16A complex ester obtained from PE, 2EHx, adipic acid, etc. Comparative oil 17A 0.8 0.2 LPt: 0.4 n-heptanoic acid: 0.4 TMHx: 0.2 Comparative oil 18A mixed oil (refrigeration oil A, 25 wt % + comparative oil 1, 75 wt %) Makeup of refrigeration oil A Alcohol: neopentyl glycol Fatty acid: 2EHx Comparative oil 19A mixed oil (refrigeration oil A, 50 wt % + comparative oil 9, 50 wt %) Makeup of refrigeration oil A Alcohol: neopentyl glycol Fatty acid: 2EHx Comparative oil 20A mixed oil (refrigeration oil A, 30 wt % + comparative oil 16, 70 wt %) Makeup of refrigeration oil A Alcohol: neopentyl glycol Fatty acid: 2EHx Note 1) Comparative oil 1A and comparative oil 15A are in use in air conditioners where R-410A, which is a current refrigerant, is used. Note 2) Although synthetic oil 18A appears to be produced from one alcohol and one fatty acid, it has been ascertained that the fatty acid was a racemate and composed of two components and, hence, the oil does not solidify. Note 3) Comparative oil 16A is in use in large refrigerated facilities or air conditioners where R-410A, 407C, 134a, and 404A, which are current refrigerants, are used. Note 4) Although synthetic oils 29A and 34A each appear to be produced from one alcohol and one fatty acid, it has been ascertained that the fatty acid was a racemate and composed of two components and, hence, the oil does not solidify. Note 5) Synthetic oil 17A is in use in refrigerated facilities or air conditioners where R-134a and 404A, which are current refrigerants, are used. Note 6) Refrigeration oil A used in comparative oils 18A to 20A is in use in refrigeration oils for HFC-refrigerant refrigerators. Two-layer separation temperatures for refrigeration oil A and refrigerant R-32 (oil content, 20 wt %): high temperature, +70° C. or higher; low temperature, −20° C. Kinematic viscosity of refrigeration oil A: 7.56 (40° C.), 2.07 (100° C.)

Test Example 1A With Respect to Kinematic Viscosities of Each Polyol Ester Oil Synthesized

Each of the polyol ester oils and comparative oils was examined for kinematic viscosity at 40° C. and 100° C. The results of the measurement are shown in Tables 3 and 4.

TABLE 3 Kinematic viscosity mm²/s mm²/s Example No. Oil No. (40° C.) (100° C.) Remarks Example 1A synthetic oil 1A 69.7 8.67 — Example 2A synthetic oil 2A 66.9 8.42 — Example 3A synthetic oil 3A 66.0 8.39 — Example 4A synthetic oil 4A 64.5 8.20 — Example 5A synthetic oil 5A 97.8 10.9 — Example 6A synthetic oil 6A 75.1 9.10 — Example 7A synthetic oil 7A 60.0 7.76 — Example 8A synthetic oil 8A 66.1 8.23 — Example 9A synthetic oil 9A 64.4 8.20 — Example 10A synthetic oil 10A 62.5 7.98 — Example 11A synthetic oil 11A 67.1 9.88 — Example 12A synthetic oil 12A 69.0 9.26 — Example 13A synthetic oil 13A 61.8 8.71 — Example 14A synthetic oil 14A 53.9 7.39 — Example 15A synthetic oil 15A 70.0 6.99 — Example 16A synthetic oil 16A 140 13.8 — Example 17A synthetic oil 17A 139 13.6 — Example 18A synthetic oil 18A 141 13.6 — Example 19A synthetic oil 19A 124 12.4 — Example 20A synthetic oil 20A 108 11.4 — Example 21A synthetic oil 21A 149 14.0 — Example 22A synthetic oil 22A 196 16.7 — Example 23A synthetic oil 23A 164 15.0 — Example 24A synthetic oil 24A 225 18.3 — Example 25A synthetic oil 25A 276 20.9 — Example 26A synthetic oil 26A 27.8 4.99 — Example 27A synthetic oil 27A 24.8 4.88 — Example 28A synthetic oil 28A 42.7 6.69 — Example 29A synthetic oil 29A 25.7 4.39 — Example 30A synthetic oil 30A 29.4 4.83 — Example 31A synthetic oil 31A 36.8 5.47 — Example 32A synthetic oil 32A 47.3 6.48 — Example 33A synthetic oil 33A 37.3 5.66 — Example 34A synthetic oil 34A 22.4 4.31 — Example 35A synthetic oil 35A 26.0 4.67 —

TABLE 4 Kinematic viscosity Comparative mm²/s mm²/s Example No. Oil No. (40° C.) (100° C.) Remarks Comparative comparative 67.8 8.34 — Example 1A oil 1A Comparative comparative 64.6 8.50 — Example 2A oil 2A Comparative comparative 88.0 11.9 — Example 3A oil 3A Comparative comparative 53.0 8.72 solidified at Example 4A oil 4A room temperature Comparative comparative 54.0 6.36 solidified at Example 5A oil 5A room temperature Comparative comparative 70.4 8.74 — Example 6A oil 6A Comparative comparative 181 17.6 — Example 7A oil 7A Comparative comparative 114 11.5 solidified at Example 8A oil 8A room temperature Comparative comparative 228 19.2 — Example 9A oil 9A Comparative comparative 116 12.9 — Example 10A oil 10A Comparative comparative 44.3 6.26 — Example 11A oil 11A Comparative comparative 34.1 5.44 — Example 12A oil 12A Comparative comparative 40.5 6.58 — Example 13A oil 13A Comparative comparative 36.4 5.60 — Example 14A oil 14A Comparative comparative 64.7 7.95 — Example 15A oil 15A Comparative comparative 226 21.8 — Example 16A oil 16A Comparative comparative 30.3 5.73 — Example 17A oil 17A Comparative comparative 33.8 5.44 — Example 18A oil 18A Comparative comparative 32.4 5.42 — Example 19A oil 19A Comparative comparative 67.4 9.42 — Example 20A oil 20A

Test 2A With Respect to Solubility with R-32

Each polyol ester oil and R-32 were enclosed in a glass tube so as to result in an oil content of 20% by weight, and the glass tube was shaken to dissolve the R-32 in the polyol ester oil. After the dissolution, the glass tube was placed in a water bath and gradually heated to measure the temperature at which the even layer separated into an oil layer and a refrigerant layer (high-temperature-side two-layer separation temperature). Meanwhile, the glass tube was placed in a cooling chamber and gradually cooled to measure the temperature at which the even layer separated into an oil layer and a refrigerant layer (low-temperature-side two-layer separation temperature).

The results of the measurements and the kinematic viscosities are both shown in Table 5 to Table 7.

TABLE 5 Refrigerant R-32/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 36A synthetic oil 1A +48 +16 69.7 Example 37A synthetic oil 2A +58 −6 66.9 Example 38A synthetic oil 3A +68 −30 66.0 Example 39A synthetic oil 4A +70 or higher −50 64.5 Example 40A synthetic oil 5A +52 +4 97.8 Example 41A synthetic oil 6A +51 +9 75.1 Example 42A synthetic oil 7A +67 −13 60.0 Example 43A synthetic oil 8A +70 or higher −50 or lower 66.1 Example 44A synthetic oil 9A +62 −2 64.4 Example 45A synthetic oil 10A +68 −24 62.5 Example 46A synthetic oil 11A +54 −12 67.1 Example 47A synthetic oil 12A +46 −1 69.0 Example 48A synthetic oil 13A +61 −18 61.8 Example 49A synthetic oil 14A +57 +7 53.9 Example 50A synthetic oil 15A +56 +10 70.0 Comparative comparative oil 1A separated separated 67.8 Example 18A throughout throughout the whole range the whole range Comparative comparative oil 2A separated separated 64.6 Example 19A throughout throughout the whole range the whole range Comparative comparative oil 3A Separated separated 88.0 Example 20A throughout throughout the whole range the whole range Comparative comparative oil 4A Separated separated 53.0 Example 21A throughout throughout the whole range the whole range Comparative comparative oil 5A +70 or higher −14 54.0 Example 22A solidified at room temperature Comparative comparative oil 6A Separated separated 70.4 Example 23A throughout throughout the whole range the whole range Comparative comparative oil separated separated 64.7 Example 24A 15A throughout throughout the whole range the whole range Comparative comparative oil separated separated 67.4 Example 25A 20A throughout throughout the whole range the whole range

TABLE 6 Refrigerant R-32/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-320 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 51A synthetic oil 16A +45 +10 140 Example 52A synthetic oil 17A +57 −14 139 Example 53A synthetic oil 18A +70 or higher −50 or lower 141 Example 54A synthetic oil 19A +70 or higher −50 or lower 124 Example 55A synthetic oil 20A +61 −3 108 Example 56A synthetic oil 21A +56 −1 149 Example 57A synthetic oil 22A +52 +8 196 Example 58A synthetic oil 23A +70 or higher −50 or lower 164 Example 59A synthetic oil 24A +53 −8 225 Example 60A synthetic oil 25A +45 +15 276 Comparative comparative oil 7A separated separated 181 Example 26A throughout throughout the whole range the whole range Comparative comparative oil 8A separated separated 114 Example 27A throughout throughout solidified the whole range the whole range at room temperature Comparative comparative oil 9A Separated separated 228 Example 28A throughout throughout the whole range the whole range Comparative comparative oil 10A Separated separated 116 Example 29A throughout throughout the whole range the whole range Comparative comparative oil 16A separated Separated 226 Example 30A throughout throughout the whole range the whole range

TABLE 7 Refrigerant R-32/small refrigerated facility (as refrigeration oil having kinematic viscosity at 40° C. of 22-50 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 61A synthetic oil 26A +66  −8 27.8 Example 62A synthetic oil 27A +70 or higher −30 24.8 Example 63A synthetic oil 28A +63  −5 42.7 Example 64A synthetic oil 29A +70 or higher −50 or lower 25.7 Example 65A synthetic oil 30A +70 or higher −48 29.4 Example 66A synthetic oil 31A +70 or higher −14 36.8 Example 67A synthetic oil 32A +70 or higher −50 or lower 47.2 Example 68A synthetic oil 33A +70 or higher −41 37.3 Example 69A synthetic oil 34A +70 or higher −39 22.4 Example 70A synthetic oil 35A +70 or higher −16 26.0 Comparative comparative oil 11A separated separated 44.3 Example 31A throughout throughout the whole range the whole range Comparative comparative oil 12A +48 +27 34.1 Example 32A Comparative comparative oil 13A +41 +25 40.5 Example 33A Comparative comparative oil 14A +44 +32 36.4 Example 34A Comparative comparative oil 17A +43 +24 30.3 Example 35A Comparative comparative oil 18A separated separated 33.8 Example 36A throughout throughout the whole range the whole range Comparative comparative oil 19A separated separated 32.4 Example 37A throughout throughout the whole range the whole range

Test Example 3A With Respect to Solubility with R-410A and Kinematic Viscosity

The high-temperature-side two-layer separation temperature and the low-temperature-side two-layer separation temperature were measured in the same manners as in Test Example 1A, except that R-410A was used as a hydrofluorocarbon-based refrigerant. The results of the measurements and the kinematic viscosities are both shown in Table 8 and Table 9.

TABLE 8 Refrigerant R-410A/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 71A synthetic oil 1A +51 −35 69.7 Example 72A synthetic oil 2A +60 −50 66.9 Example 73A synthetic oil 3A +65 −50 or lower 66.0 Example 74A synthetic oil 4A +70 or higher −50 64.5 Example 75A synthetic oil 5A +54 −41 97.8 Example 76A synthetic oil 6A +53 −39 75.1 Example 77A synthetic oil 7A +64 −50 or lower 60.0 Example 78A synthetic oil 8A +70 or higher −50 or lower 66.1 Example 79A synthetic oil 9A +59 −42 64.4 Example 80A synthetic oil 10A +66 −50 or lower 62.5 Example 81A synthetic oil 11A +52 −50 or lower 67.1 Example 82A synthetic oil 12A +48 −50 or lower 69.0 Example 83A synthetic oil 13A +59 −50 or lower 61.8 Example 84A synthetic oil 14A +57 −31 53.9 Example 85A synthetic oil 15A +52 −22 70.0 Comparative comparative oil 3A separated separated 88.0 Example 38A throughout throughout the whole range the whole range Comparative comparative oil 5A +64 −50 or lower 54.0 Example 39A solidified at room temperature Comparative comparative oil 6A separated separated 70.4 Example 40A throughout throughout the whole range the whole range

TABLE 9 Refrigerant R-410A/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-320 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 86A synthetic oil 16A +47 −35 140 Example 87A synthetic oil 17A +70 or higher −50 or lower 139 Example 88A synthetic oil 18A +70 or higher −50 or lower 141 Example 89A synthetic oil 19A +70 or higher −50 or lower 124 Example 90A synthetic oil 20A +58 −43 108 Example 91A synthetic oil 21A +53 −41 149 Example 92A synthetic oil 22A +50 −32 196 Example 93A synthetic oil 23A +70 or higher −50 or lower 164 Example 94A synthetic oil 24A +52 −50 or lower 225 Example 95A synthetic oil 25A +43 −25 276 Comparative comparative oil 7A separated separated 181 Example 41A throughout throughout the whole range the whole range Comparative comparative oil 8A +27  +7 114 Example 42A solidified at room temperature Comparative comparative oil 9A separated separated 228 Example 43A throughout throughout the whole range the whole range Comparative comparative oil 10A separated separated 116 Example 44A throughout throughout the whole range the whole range

Test Example 4A With Respect to Solubility with HFO-1234yf and Kinematic Viscosity

The high-temperature-side two-layer separation temperature and the low-temperature-side two-layer separation temperature were measured in the same manners as in Test Example 1A, except that HFO-1234yf was used as a hydrofluorocarbon-based refrigerant. The results of the measurements and the kinematic viscosities are both shown in Table 10 to Table 12.

TABLE 10 Refrigerant HFO-1234yf/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 96A synthetic oil 1A +70 or higher −50 or lower 69.7 Example 97A synthetic oil 2A +70 or higher −50 or lower 66.9 Example 98A synthetic oil 3A +70 or higher −50 or lower 66.0 Example 99A synthetic oil 4A +70 or higher −50 or lower 64.5 Example 100A synthetic oil 5A +70 or higher −50 or lower 97.8 Example 101A synthetic oil 6A +70 or higher −50 or lower 75.1 Example 102A synthetic oil 7A +70 or higher −50 or lower 60.0 Example 103A synthetic oil 8A +70 or higher −50 or lower 66.1 Example 104A synthetic oil 9A +70 or higher −50 or lower 64.4 Example 105A synthetic oil 10A +70 or higher −50 or lower 62.5 Example 106A synthetic oil 11A +70 or higher −50 or lower 67.1 Example 107A synthetic oil 12A +70 or higher −50 or lower 69.0 Example 108A synthetic oil 13A +70 or higher −50 or lower 61.8 Example 109A synthetic oil 14A +70 or higher −50 or lower 53.9 Example 110A synthetic oil 15A +70 or higher −50 or lower 70.0 Comparative comparative oil 4A +70 or higher −50 or lower 53.0 Example 45A solidified at room temperature Comparative comparative oil 5A +70 or higher −50 or lower 54.0 Example 46A solidified at room temperature

TABLE 11 Refrigerant HFO-1234yf/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-320 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 111A synthetic oil 16A +70 or higher −50 or lower 140 Example 112A synthetic oil 17A +70 or higher −50 or lower 139 Example 113A synthetic oil 18A +70 or higher −50 or lower 141 Example 114A synthetic oil 19A +70 or higher −50 or lower 124 Example 115A synthetic oil 20A +70 or higher −50 or lower 108 Example 116A synthetic oil 21A +70 or higher −50 or lower 149 Example 117A synthetic oil 22A +70 or higher −50 or lower 196 Example 118A synthetic oil 23A +70 or higher −50 or lower 164 Example 119A synthetic oil 24A +70 or higher −50 or lower 225 Example 120A synthetic oil 25A +70 or higher −50 or lower 276 Comparative comparative oil 8A separated separated 114 Example 47A throughout throughout solidified the whole range the whole range at room temperature

TABLE 12 Refrigerant HFO-1234yf/small refrigerated facility (as refrigeration oil having kinematic viscosity at 40° C. of 22-50 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 121A synthetic oil 26A +70 or higher −50 or lower 27.8 Example 122A synthetic oil 27A +70 or higher −50 or lower 24.8 Example 123A synthetic oil 28A +70 or higher −50 or lower 42.7 Example 124A synthetic oil 29A +70 or higher −50 or lower 25.7 Example 125A synthetic oil 30A +70 or higher −50 or lower 29.4 Example 126A synthetic oil 31A +70 or higher −50 or lower 36.8 Example 127A synthetic oil 32A +70 or higher −50 or lower 47.2 Example 128A synthetic oil 33A +70 or higher −50 or lower 37.3 Example 129A synthetic oil 34A +70 or higher −50 or lower 22.4 Example 130A synthetic oil 35A +70 or higher −50 or lower 26.0 Comparative comparative oil 11A +70 or higher −50 or lower 17.2 Example 48A Comparative comparative oil 12A +70 or higher −50 or lower 19.7 Example 49A Comparative comparative oil 13A +70 or higher −50 or lower 18.8 Example 50A

Test Example 5A With Respect to Solubility with HFO-1234ze(E) and Kinematic Viscosity

The high-temperature-side two-layer separation temperature and the low-temperature-side two-layer separation temperature were measured in the same manners as in Test Example 1A, except that HFO-1234ze(E) was used as a hydrofluorocarbon-based refrigerant. The results of the measurements and the kinematic viscosities are both shown in Table 13 to Table 15.

TABLE 13 Refrigerant HFO-1234ze(E)/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 131A synthetic oil 1A +70 or higher −50 or lower 69.7 Example 132A synthetic oil 2A +70 or higher −50 or lower 66.9 Example 133A synthetic oil 3A +70 or higher −50 or lower 66.0 Example 134A synthetic oil 4A +70 or higher −50 or lower 64.5 Example 135A synthetic oil 5A +70 or higher −50 or lower 97.8 Example 136A synthetic oil 6A +70 or higher −50 or lower 75.1 Example 137A synthetic oil 7A +70 or higher −50 or lower 60.0 Example 138A synthetic oil 8A +70 or higher −50 or lower 66.1 Example 139A synthetic oil 9A +70 or higher −50 or lower 64.4 Example 140A synthetic oil 10A +70 or higher −50 or lower 62.5 Example 141A synthetic oil 11A +70 or higher −50 or lower 67.1 Example 142A synthetic oil 12A +70 or higher −50 or lower 69.0 Example 143A synthetic oil 13A +70 or higher −50 or lower 61.8 Example 144A synthetic oil 14A +70 or higher −50 or lower 53.9 Example 145A synthetic oil 15A +70 or higher −50 or lower 70.0 Comparative comparative oil 4A +70 or higher −50 or lower 53.0 Example 51A solidified at room temperature Comparative comparative oil 5A +70 or higher −50 or lower 54.0 Example 52A solidified at room temperature

TABLE 14 Refrigerant HFO-1234ze(E)/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-320 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 146A synthetic oil 16A +70 or higher −50 or lower 140 Example 147A synthetic oil 17A +70 or higher −50 or lower 139 Example 148A synthetic oil 18A +70 or higher −50 or lower 141 Example 149A synthetic oil 19A +70 or higher −50 or lower 124 Example 150A synthetic oil 20A +70 or higher −50 or lower 108 Example 151A synthetic oil 21A +70 or higher −50 or lower 149 Example 152A synthetic oil 22A +70 or higher −50 or lower 196 Example 153A synthetic oil 23A +70 or higher −50 or lower 164 Example 154A synthetic oil 24A +70 or higher −50 or lower 225 Example 155A synthetic oil 25A +70 or higher −50 or lower 276 Comparative comparative oil 8A separated separated 114 Example 53A throughout throughout solidified the whole range the whole range at room temperature

TABLE 15 Refrigerant HFO-1234ze(E)/small refrigerated facility (as refrigeration oil having kinematic viscosity at 40° C. of 22-50 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 156A synthetic oil 26A +70 or higher −50 or lower 27.8 Example 157A synthetic oil 27A +70 or higher −50 or lower 24.8 Example 158A synthetic oil 28A +70 or higher −50 or lower 42.7 Example 159A synthetic oil 29A +70 or higher −50 or lower 25.7 Example 160A synthetic oil 30A +70 or higher −50 or lower 29.4 Example 161A synthetic oil 31A +70 or higher −50 or lower 36.8 Example 162A synthetic oil 32A +70 or higher −50 or lower 47.2 Example 163A synthetic oil 33A +70 or higher −50 or lower 37.3 Example 164A synthetic oil 34A +70 or higher −50 or lower 22.4 Example 165A synthetic oil 35A +70 or higher −50 or lower 26.0 Comparative comparative oil 11A +70 or higher −50 or lower 17.2 Example 54A Comparative comparative oil 12A +70 or higher −50 or lower 19.7 Example 55A Comparative comparative oil 13A +70 or higher −50 or lower 18.8 Example 56A

Test Example 6A With Respect to Lubricity of Refrigeration Oils

Examples 1A, 2A, 3A, 4A, and 8A and Comparative Example 1A, which is a current refrigeration oil for R-410A air conditioners, were evaluated with a Falex tester. The results thereof are shown in Table 16.

(Test Conditions)

-   -   Test apparatus: Falex tester (PIN-VEE BLOCK)     -   Test temperature: 80° C.     -   Test load: 150 lbs     -   Test period: 4 hr     -   Rotation speed: 290 rpm

TABLE 16 Example/Comparative Example No. Comparative Example Example Example Example Example Example 166A 167A 168A 169A 170A 57A Oil No. synthetic synthetic synthetic synthetic synthetic comparative oil 1A oil 2A oil 3A oil 4A oil 8A oil 1A 2EHx molar 1 0.5 0.32 0.15 0 0.52 ratio DiPE molar 0.34 0.44 0.46 0.45 0.5 0 ratio Average 766 700 670 632 615 668 molecular weight Wear ratio 0.61 0.92 0.63 0.98 0.51 1 (Comparative Example 1A (current oil) being taken as 1)

Test Example 7A With Respect to Hygroscopicity

Example 2A and Comparative Example 1A, which is a current refrigeration oil for R-410A air conditioners, were evaluated through a hygroscopicity test. The results thereof are shown in Table 17.

(Test Conditions)

Test apparatus: A hygroscopicity tester based on a combination of a humidifier, acrylic case, turntable, fan, heater, hygrometer, and thermometer was produced and used.

Test temperature: 30° C.

Test humidity: 80% RH

Surface area of specimen: 21.2 cm²

TABLE 17 Comparative Example 171A/ Example 171A Example 58A Comparative Test Synthetic oil 2A Comparative oil 1A Example 58A period, moisture content, moisture Moisture hr ppm content, ppm content ratio 0 24 22 1.09 1 148 174 0.85 2 261 350 0.74 3 334 500 0.67 4 431 640 0.67 6 605 790 0.77 8 780 921 0.85 10 932 1030 0.90 15 1200 1180 1.02 26 1587 1336 1.19 48 2150 1459 1.47 72 2296 1580 1.52 96 2523 1622 1.55

The open time which was supposed when facility dealers handled refrigeration oils was set at 0.5 to 3 hours among the test periods shown in Table 17, and refrigeration oils were compared in the degree of moisture absorption in a range including shorter and longer periods. The results thereof are shown in FIG. 1.

Test Example 8A With Respect to Hydrolytic Resistance

A polyol ester oil which had a moisture content of 500 ppm and to which an antioxidant and an acid scavenger had been added as additives was enclosed in a glass tube together with refrigerant R-32 and an iron wire, copper wire, or aluminum wire as a catalyst, and a heating test was conducted for 14 days in a 175° C. thermostatic chamber. After completion of the heating period, the contents were examined for appearance, color, any change in the catalyst, and precipitate. Furthermore, the polyol ester oil which had undergone the test was taken out and examined for acid value. The results thereof are shown in Table 18 and Table 19.

TABLE 18 Example/Comparative Example No. Example Example Example Example Example Example 172A 173A 174A 175A 176A 177A Oil No. synthetic synthetic synthetic synthetic synthetic synthetic oil 1A oil 2A oil 3A oil 4A oil 5A oil 6A Appearance transparent transparent transparent transparent transparent transparent Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Change of catalyst, light light light light light light iron brown brown brown brown brown brown Change of catalyst, no no no no no no copper change change change change change change Change of catalyst, no no no no no no aluminum change change change change change change Precipitate none none none none none none Acid value, 0.04 0.04 0.04 0.05 0.04 0.04 mg-KOH/g

TABLE 19 Example/Comparative Example No. Comparative Comparative Example Example Example Example Example Example 178A 179A 180A 181A 59A 60A Oil No. synthetic synthetic synthetic synthetic comparative comparative oil 7A oil 8A oil 9A oil 10A oil 1A oil 15A Appearance transparent transparent transparent transparent transparent transparent Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Change of catalyst, light light light light light light iron brown brown brown brown brown brown Change of catalyst, no no no no no no copper change change change change change change Change of catalyst, no no no no no no aluminum change change change change change change Precipitate none none none none none none Acid value, 0.04 0.04 0.04 0.05 0.04 0.05 mg-KOH/g Note 1) Comparative oil 1A and comparative oil 15A are in use in air conditioners where R-410A, which is a current refrigerant, is used.

Test Example 9A With Respect to Other Properties

Density, color, flash point, pour point, kinematic viscosity, viscosity index, and total acid number, as properties required of refrigeration oils, are shown in Table 20 to Table 24 on the basis of Examples and Comparative Examples.

TABLE 20 (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Example/Comparative Example No. Example Example Example Example Example 182A 183A 184A 185A 186A Oil No. synthetic synthetic synthetic synthetic synthetic oil 1A oil 2A oil 3A oil 4A oil 5A Density, 15° C. 0.99 1.00 1.01 1.02 1.00 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −35 −37.5 −40 −42.5 −35 Kinematic viscosity, 40° C. 69.7 66.9 66.0 64.5 97.8 mm²/s Kinematic viscosity, 100° C. 8.67 8.42 8.39 8.20 10.9 mm²/s Viscosity index 95 94 95 95 96 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g

TABLE 21 (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Example/Comparative Example No. Example Example Example Example Example 187A 188A 189A 190A 191A Oil No. synthetic synthetic synthetic synthetic synthetic oil 6A oil 7A oil 8A oil 9A oil 10A Density, 15° C. 1.02 0.98 1.03 0.97 1.00 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −35 −40 −37.5 −40 −35 Kinematic viscosity, 40° C. 75.1 60.0 66.1 64.4 62.5 mm²/s Kinematic viscosity, 9.10 7.76 8.23 8.20 7.98 100° C. mm²/s Viscosity index 94 91 91 91 92 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g

TABLE 22 (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Example/Comparative Example No. Comparative Example Example Example Example Example 192A 193A 194A 195A 61A Oil No. synthetic synthetic synthetic synthetic comparative oil 11A oil 12A oil 13A oil 15A oil 1A Density, 15° C. 1.03 1.01 0.98 1.03 0.959 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −47.5 −42.5 −42.5 −35 −40 Kinematic viscosity, 40° C. 67.1 69.0 61.8 70.0 67.8 mm²/s Kinematic viscosity, 100° C. 9.88 9.26 8.71 6.99 8.34 mm²/s Viscosity index 130 111 115 61 90 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g Note 1) Comparative oil 1A is a polyol ester in use in air conditioners where R-410A, which is a current refrigerant, is used.

TABLE 23 (as refrigeration oil having kinematic viscosity at 40° C. of 100-320 mm²/s) Example/Comparative Example No. Comparative Example Example Example Example Example 196A 197A 198A 199A 62A Oil No. synthetic synthetic synthetic synthetic comparative oil 16A oil 17A oil 24A oil 25A oil 16A Density, 15° C. 1.01 1.02 1.00 0.99 1.02 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 224 Pour point, ° C. −35 −37.5 −35 −35 −32.5 Kinematic viscosity, 40° C. 140 139 225 276 226 mm²/s Kinematic viscosity, 100° C. 13.8 13.6 18.3 20.9 21.8 mm²/s Viscosity index 94 93 89 89 116 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g Note 1) Comparative oil 16A is a polyol ester in use in large refrigerated facilities or air conditioners where R-410A, R-134a, and the like, which are current refrigerants, are used.

TABLE 24 (as refrigeration oil having kinematic viscosity at 40° C. of 22-50 mm²/s) Example/Comparative Example No. Compartive Example Example Example Example Example 200A 201A 202A 203A 63A Oil No. synthetic synthetic synthetic synthetic comparative oil 30A oil 31A oil 32A oil 35A oil 17A Density, 15° C. 1.00 0.99 1.02 0.99 0.99 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −42.5 −40 −42.5 −45 −50 Kinematic viscosity, 40° C. 29.4 36.8 47.3 26.0 30.3 mm²/s Kinematic viscosity, 100° C. 4.83 5.47 6.48 4.67 5.73 mm²/s Viscosity index 76 76 82 93 133 Moisture content, ppm 25 25 25 25 50 Total acid number, 0.01 0.01 0.01 0.01 0.02 mg-KOH/g Note 1) Comparative oil 17A is a polyol ester in use in small refrigerated facilities where R-134a, R-404A, and the like, which are current refrigerants, are used.

(List of Polyol Ester Oils for Each Raw Material Combination)

The Examples and the Comparative Examples are arranged with respect to each of raw material combinations to show that various viscosities and solubility with various refrigerants are obtained by changing the ratio of raw materials. The relationships between the raw material combination and kinematic viscosity or refrigerated facilities/air conditioners to which the oil is applicable are as shown in the following Table 25 to Table 34.

TABLE 25 Raw material combination (1): alcohols, PE and DiPE; acid 1, 2MBu; acid 2, 2EHx Kinematic viscosity Refrigerating Oil No. PE DiPE 2MBu 2EHx (40° C.) mm²/s apparatus Synthetic 0.60 0.40 0.4 0.6 69.7 air conditioner oil 1A Synthetic 0.55 0.45 0.5 0.5 66.9 air conditioner oil 2A Synthetic 0.55 0.45 0.7 0.3 66.0 air conditioner oil 3A Synthetic 0.55 0.45 0.85 0.15 64.5 air conditioner oil 4A Synthetic 0.30 0.70 0.5 0.5 97.8 air conditioner oil 5A Synthetic 0.55 0.45 0.45 0.55 75.1 air conditioner oil 6A Synthetic 0.0 1.0 0.5 0.5 140 large refrigerated facility or oil 16A air conditioner Synthetic 0.0 1.0 0.65 0.35 139 large refrigerated facility oil 17A or air conditioner Synthetic 0.0 1.0 1.0 0.0 141 large refrigerated facility oil 18A or air conditioner Synthetic 0.10 0.90 1.0 0.0 124 large refrigerated facility oil 19A or air conditioner Synthetic 1.0 0.0 1.0 0.0 25.7 small refrigerated facility oil 29A Synthetic 1.0 0.0 0.75 0.25 29.4 small refrigerated facility oil 30A Synthetic 1.0 0.0 0.5 0.5 36.8 small refrigerated facility oil 31A Synthetic 0.70 0.30 0.85 0.15 47.2 small refrigerated facility oil 32A Comparative 0.65 0.35 0.0 1.0 70.4 — oil 6A Comparative 1.0 0.0 0.0 1.0 44.3 — oil 11A

TABLE 26 Raw material combination (2): alcohols, PE and DiPE; acid 1, 2MBu; acid 2, TMHx Kinematic viscosity Refrigerating Oil No. PE DiPE 2MBu TMHx (40° C.) mm²/s apparatus Synthetic 1.0 0.0 0.5 0.5 60.0 air conditioner oil 7A Synthetic 0.50 0.50 1.0 0.0 66.1 air conditioner oil 8A Synthetic 1.0 0.0 0.4 0.6 64.4 air conditioner oil 9A Synthetic 0.85 0.15 0.6 0.4 62.5 air conditioner oil 10A Synthetic 0.0 1.0 1.0 0.0 141 large refrigerated facility oil 18A or air conditioner Synthetic 0.10 0.90 1.0 0.0 124 large refrigerated facility oil 19A or air conditioner Synthetic 0.70 0.30 0.5 0.5 108 large refrigerated facility oil 20A or air conditioner Synthetic 0.50 0.50 0.5 0.5 149 large refrigerated facility oil 21A or air conditioner Synthetic 0.30 0.70 0.5 0.5 196 large refrigerated facility oil 22A or air conditioner Synthetic 0.0 1.0 0.9 0.1 164 large refrigerated facility oil 23A or air conditioner Synthetic 0.0 1.0 0.65 0.35 225 large refrigerated facility oil 24A or air conditioner Synthetic 0.0 1.0 0.5 0.5 276 large refrigerated facility oil 25A or air conditioner Synthetic 1.0 0.0 1.0 0.0 25.7 small refrigerated facility oil 29A Synthetic 1.0 0.0 0.75 0.25 37.3 small refrigerated facility oil 33A Comparative 1.0 0.0 0.0 1.0 114 — oil 8A solidified at room temperature

TABLE 27 Raw material combination (3): alcohols, PE and DiPE; acid 1, LPt; acid 2, 2EHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE LPt 2EHx mm²/s apparatus Synthetic 1.0 0.0 0.5 0.5 27.8 small refrigerated oil 26A facility Comparative 0.65 0.35 0.0 1.0 70.4 — oil 6A Comparative 1.0 0.0 0.0 1.0 44.3 — oil 11A Comparative 1.0 0.0 0.25 0.75 34.1 — oil 12A

TABLE 28 Raw material combination (4): alcohols, PE and DiPE; acid 1, LPt; acid 2, TMHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE LPt TMHx mm²/s apparatus Synthetic 0.0 1.0 0.8 0.2 67.1 air conditioner oil 11A Synthetic 1.0 0.0 0.75 0.25 24.8 small refrigerated oil 27A facility Synthetic 1.0 0.0 0.5 0.5 42.7 small refrigerated oil 28A facility Comparative 1.0 0.0 0.0 1.0 114 — oil 8A solidified at room temper- ature

TABLE 29 Raw material combination (5): alcohols, PE and DiPE; acid 1, 2MPt; acid 2, 2EHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2MPt 2EHx mm²/s apparatus Synthetic 0.25 0.75 0.8 0.2 69.0 air conditioner oil 12A Synthetic 0.25 0.75 1.0 0.0 61.8 air conditioner oil 13A Synthetic 1.0 0.0 1.0 0.0 22.4 small refrigerated oil 34A facility Synthetic 1.0 0.0 0.75 0.25 26.0 small refrigerated oil 35A facility Comparative 0.65 0.35 0.0 1.0 70.4 — oil 6A Comparative 0.0 1.0 0.35 0.65 116 — oil 10A Comparative 1.0 0.0 0.0 1.0 44.3 — oil 11A Comparative 1.0 0.0 0.25 0.75 36.4 — oil 14A

TABLE 30 Raw material combination (6): alcohols, PE and DiPE; acid 1, 2MPt; acid 2, TMHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2MPt TMHx mm²/s apparatus Synthetic 0.25 0.75 1.0 0.0 61.8 air conditioner oil 13A Synthetic 1.0 0.0 0.5 0.5 53.9 air conditioner oil 14A Synthetic 1.0 0.0 1.0 0.0 22.4 small oil 34A refrigerated facility Comparative 1.0 0.0 0.0 1.0 114 — oil 8A solidified at room temper- ature

TABLE 31 Raw material combination (7): alcohols, PE and DiPE; acid 1, 2EBu; acid 2, TMHx Kinematic viscosity Refrigerating Oil No. PE DiPE 2EBu TMHx (40° C.) mm²/s apparatus Synthetic 1.0 0.0 0.75 0.25 70.0 air oil 15A conditioner Comparative 1.0 0.0 0.0 1.0 114 — oil 8A solidified at room temperature

TABLE 32 Raw material combination (8): alcohols, PE and DiPE; acid 1, LHx; acid 2, TMHx Kinematic viscosity Refrigerating Oil No. PE DiPE LHx TMHx (40° C.) mm²/s apparatus Comparative 1.0 0.0 0.25 0.75 64.6 — oil 2A Comparative 0.0 1.0 0.65 0.35 88.0 — oil 3A Comparative 0.0 1.0 1.0 0.0 53.0 — oil 4A solidified at room temperature Comparative 0.0 1.0 0.35 0.65 181 — oil 7A Comparative 1.0 0.0 0.0 1.0 114 — oil 8A solidified at room temperature Comparative 1.0 0.0 0.5 0.5 40.5 — oil 13A

TABLE 33 Raw material combination (9): alcohols, PE and DiPE; acid 1, 2EHx; acid 2, TMHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2EHx TMHx mm²/s apparatus Comparative 1.0 0.0 0.5 0.5 67.8 air oil 1A conditioner Comparative 0.65 0.35 1.0 0.0 70.4 — oil 6A Comparative 1.0 0.0 0.0 1.0 114 — oil 8A solidified at room temperature Comparative 0.0 1.0 0.5 0.5 228 — oil 9A Comparative 1.0 0.0 1.0 0.0 44.3 — oil 11A

TABLE 34 Other combinations (conventional refrigeration oils) Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE Acids mm²/s apparatus Comparative 0.8 0.2 LPt: 0.4 30.3 small oil 17A n-heptanoic acid: refrigerated 0.4 facility MHx: 0.2 Comparative refrigerant R-410A/ether oil 64.7 air oil 15A for air conditioner conditioner Comparative complex ester obtained from 226 large oil 16A PE, 2EHx, adipic acid, etc. refrigerated facility or air conditioner Refrigerating Alcohol: neopentyl glycol 7.56 domestic machine Fatty acid: 2EHx refrigerator oil A

The relationship between each raw material combination and the solubility with each refrigerant (low-temperature-side two-layer separation temperature) is as shown in the following Table 35 to Table 44.

TABLE 35 Alcohols, PE and DiPE; acid 1, 2MBu; acid 2, 2EHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. HFO- Oil No. PE DiPE 2MBu 2EHx R-32 R-410A 1234ze(E) Synthetic 0.60 0.40 0.4 0.6 +16 −35 −50 or lower oil 1A Synthetic 0.55 0.45 0.5 0.5  −6 −50 −50 or lower oil 2A Synthetic 0.55 0.45 0.7 0.3 −30 −50 or lower −50 or lower oil 3A Synthetic 0.55 0.45 0.85 0.15 −50 −50 −50 or lower oil 4A Synthetic 0.30 0.70 0.5 0.5  +4 −41 −50 or lower oil 5A Synthetic 0.55 0.45 0.45 0.55  +9 −39 −50 or lower oil 6A Synthetic 0.0 1.0 0.5 0.5 +10 −35 −50 or lower oil 16A Synthetic 0.0 1.0 0.65 0.35 −14 −50 or lower −50 or lower oil 17A Synthetic 0.0 1.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 18A Synthetic 0.10 0.90 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 19A Synthetic 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 29A Synthetic 1.0 0.0 0.75 0.25 −48 −50 or lower −50 or lower oil 30A Synthetic 1.0 0.0 0.5 0.5 −14 −50 or lower −50 or lower oil 31A Synthetic 0.70 0.30 0.85 0.15 −50 or lower −50 or lower −50 or lower oil 32A Comparative 0.65 0.35 0.0 1.0 separated separated −50 or lower oil 6A throughout throughout the whole the whole range range Comparative 1.0 0.0 0.0 1.0 separated +17 −50 or lower oil 11A throughout the whole range

TABLE 36 Alcohols, PE and DiPE; acid 1, 2MBu; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. HFO- Oil No. PE DiPE 2MBu TMHx R-32 R-410A 1234ze(E) Synthetic 1.0 0.0 0.5 0.5 −13  −50 or lower −50 or lower oil 7A Synthetic 0.50 0.50 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 8A Synthetic 1.0 0.0 0.4 0.6 −2 −42 −50 or lower oil 9A Synthetic 0.85 0.15 0.6 0.4 −24  −50 or lower −50 or lower oil 10A Synthetic 0.0 1.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 18A Synthetic 0.10 0.90 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 19A Synthetic 0.70 0.30 0.5 0.5 −3 −43 −50 or lower oil 20A Synthetic 0.50 0.50 0.5 0.5 −1 −41 −50 or lower oil 21A Synthetic 0.30 0.70 0.5 0.5 +8 −32 −50 or lower oil 22A Synthetic 0.0 1.0 0.9 0.1 −50 or lower −50 or lower −50 or lower oil 23A Synthetic 0.0 1.0 0.65 0.35 −2 −50 or lower −50 or lower oil 24A Synthetic 0.0 1.0 0.5 0.5 +15  −25 −50 or lower oil 25A Synthetic 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 29A Synthetic 1.0 0.0 0.75 0.25 −30  −50 or lower −50 or lower oil 33A Comparative 1.0 0.0 0.0 1.0 separated +7 −50 or lower oil 8A throughout the whole range

TABLE 37 Alcohols, PE and DiPE; acid 1, LPt; acid 2, 2EHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE LPt 2EHx R-32 R-410A HFO-1234ze(E) Synthetic 1.0 0.0 0.5 0.5  −8 −49 −50 or lower oil 26A Comparative 0.65 0.35 0.0 1.0 separated separated −50 or lower oil 6A throughout throughout the whole the whole range range Comparative 1.0 0.0 0.0 1.0 separated +17 −50 or lower oil 11A throughout the whole range Comparative oil 1.0 0.0 0.25 0.75 +27 −20 −50 or lower 12A

TABLE 38 Alcohols, PE and DiPE; acid 1, LPt; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE LPt TMHx R-32 R-410A HFO-1234ze(E) Synthetic 0.0 1.0 0.8 0.2 −12 −50 or lower −50 or lower oil 11A Synthetic 1.0 0.0 0.75 0.25 −30 −50 or lower −50 or lower oil 27A Synthetic 1.0 0.0 0.5 0.5  −5 −44 −50 or lower oil 28A Comparative 1.0 0.0 0.0 1.0 separated  +7 −50 or lower oil 8A throughout the whole range

TABLE 39 Alcohols, PE and DiPE; acid 1, 2MPt; acid 2, 2EHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2MPt 2EHx R-32 R-410A HFO-1234ze(E) Synthetic 0.25 0.75 0.8 0.2  −1 −50 or lower −50 or lower oil 12A Synthetic 0.25 0.75 1.0 0.0 −18 −50 or lower −50 or lower oil 13A Synthetic 1.0 0.0 1.0 0.0 −34 −50 or lower −50 or lower oil 34A Synthetic 1.0 0.0 0.75 0.25 −16 −50 or lower −50 or lower oil 35A Comparative 0.65 0.35 0.0 1.0 separated Separated −50 or lower oil 6A throughout throughout the whole the whole range range Comparative 0.0 1.0 0.35 0.65 separated separated −50 or lower oil 10A throughout throughout the whole the whole range range Comparative 1.0 0.0 0.0 1.0 separated +17 −50 or lower oil 11A throughout the whole range Comparative 1.0 0.0 0.25 0.75 +32 −19 −50 or lower oil 14A

TABLE 40 Alcohols, PE and DiPE; acid 1, 2MPt; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2MPt 2EHx R-32 R-410A HFO-1234ze(E) Synthetic 0.25 0.75 1.0 0.0 −18 −50 or lower −50 or lower oil 13A Synthetic 1.0 0.0 0.5 0.5  +7 −31 −50 or lower oil 14A Synthetic 1.0 0.0 1.0 0.0 −34 −50 or lower −50 or lower oil 34A Comparative 1.0 0.0 0.0 1.0 separated  +7 −50 or lower oil 8A throughout the whole range

TABLE 41 Alcohols, PE and DiPE; acid 1, 2EBu; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2EBu TMHx R-32 R-410A HFO-1234ze(E) Synthetic 1.0 0.0 0.75 0.25 +10 −22 −50 or lower oil 15A Comparative 1.0 0.0 0.0 1.0 separated +7 −50 or lower oil 8A throughout the whole range

TABLE 42 Alcohols, PE and DiPE; acid 1, LHx; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE LHx TMHx R-32 R-410A HFO-1234ze(E) Comparative 1.0 0.0 0.25 0.75 separated −8 −50 or lower oil 2A throughout the whole range Comparative 0.0 1.0 0.65 0.35 separated separated −50 or lower oil 3A throughout throughout the whole the whole range range Comparative 0.0 1.0 0.35 0.65 separated separated −50 or lower oil 7A throughout throughout the whole the whole range range Comparative 1.0 0.0 0.0 1.0 separated +7 −50 or lower oil 8A throughout the whole range Comparative 1.0 0.0 0.5 0.5 +25 −19  −50 or lower oil 13A

TABLE 43 Alcohols, PE and DiPE; acid 1, 2EHx; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2EHx TMHx R-32 R-410A HFO-1234ze(E) Comparative 1.0 0.0 0.5 0.5 separated +8 −50 or lower oil 1A throughout the whole range Comparative 0.65 0.35 1.0 0.0 separated separated −50 or lower oil 6A throughout throughout the whole the whole range range Comparative 1.0 0.0 0.0 1.0 separated +7 −50 or lower oil 8A throughout the whole range Comparative 0.0 1.0 0.5 0.5 separated separated −50 or lower oil 9A throughout throughout the whole the whole range range Comparative 1.0 0.0 1.0 0.0 separated +17  −50 or lower oil 11A throughout the whole range

TABLE 44 Other combinations Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. HFO- Oil No. PE DiPE Acids R-32 R-410A 1234ze(E) Comparative 0.8 0.2 LPt: 0.4 +24 −23 −50 or lower oil 17A n-heptanoic acid: 0.4 TMHx: 0.2 Comparative refrigerant R-410A/ether oil separated −51 −50 or lower oil 15A for air conditioner throughout the whole range Comparative complex ester obtained from Separated −44 −50 or lower oil 16A PE, 2EHx, adipic acid, etc. throughout Refrigerating Alcohol: neopentyl glycol −20 −50 or lower −50 or lower machine Fatty acid: 2EHx oil A

As shown in Table 23 to Table 32, the polyol ester oils each produced by esterifying an alcohol ingredient obtained by mixing pentaerythritol with dipentaerythritol and a fatty acid ingredient composed of at least one of pentanoic acid and hexanoic acid and at least one of octanoic acid and nonanoic acid are made to have various values of viscosity by changing the proportions of the raw materials with respect to each of specific raw material combinations.

Furthermore, as shown in Test Examples 1A to 4A and Table 33 to Table 42, refrigeration oil compositions which are excellent in terms of solubility and lubricity can be produced by using polyol ester oils each produced by esterifying an alcohol ingredient obtained by mixing pentaerythritol with dipentaerythritol and a fatty acid ingredient composed of at least one of pentanoic acid and hexanoic acid and at least one of octanoic acid and nonanoic acid, in accordance with the kinds of hydrofluorocarbon-based refrigerants. Moreover, as shown in Test Examples 5A to 8A, the polyol ester oils produced are equal or superior to conventional refrigeration oils in other performances and, by incorporating additives thereinto as in conventional products, the polyol ester oils can be rendered usable also in refrigerated facilities employing refrigerants having a low global warming potential, such as refrigerant R-32, as in apparatus in which R-410A, a conventional refrigerant, is used.

<Test B: Refrigeration Oil Compositions for Hydrocarbon-Based Refrigerants>

The alcohol ingredients and fatty acid ingredients shown in Table B were esterified to produce polyol ester oils. In the table, PE represents pentaerythritol, DiPE represents dipentaerythritol, LPt represents normal pentanoic acid (a pentanoic acid), 2 MBu represents DL-2-methylbutanoic acid (a pentanoic acid), LHx represents normal hexanoic acid (a hexanoic acid), 2 MPt represents DL-2-methylpentanoic acid (a hexanoic acid), 2EBu represents 2-ethylbutanoic acid (a hexanoic acid), 2EHx represents a 2-ethylhexanoic acid (an octanoic acid), and TMHx represents 3,5,5-trimethylhexanoic acid (a nonanoic acid), and the mixing proportion of each alcohol ingredient to the fatty acid ingredient is in molar ratio. A mineral oil (comparative oil 15B) for refrigerant R-290 was also used as a comparative oil.

TABLE B (Polyol ester oils used in Examples and Comparative Examples) Alcohol ingredient Fatty acid ingredient Oil No. PE DiPE Acid 1 Acid 2 Synthetic oil 1B 0.60 0.40 2MBu: 0.4 2EHx: 0.6 Synthetic oil 2B 0.55 0.45 2MBu: 0.5 2EHx: 0.5 Synthetic oil 3B 0.55 0.45 2MBu: 0.7 2EHx: 0.3 Synthetic oil 4B 0.55 0.45 2MBu: 0.85 2EHx: 0.15 Synthetic oil 5B 0.30 0.70 2MBu: 0.5 2EHx: 0.5 Synthetic oil 6B 0.55 0.45 2MBu: 0.45 2EHx: 0.55 Synthetic oil 7B 1.0 0.0 2MBu: 0.5 TMHx: 0.5 Synthetic oil 8B 0.50 0.50 2MBu: 1.0 TMHx: 0.0 Synthetic oil 9B 1.0 0.0 2MBu: 0.4 TMHx: 0.6 Synthetic oil 10B 0.85 0.15 2MBu: 0.6 TMHx: 0.4 Synthetic oil 11B 0.0 1.0 LPt: 0.8 TMHx: 0.2 Synthetic oil 12B 0.25 0.75 2MPt: 0.8 2EHx: 0.2 Synthetic oil 13B 0.25 0.75 2MPt: 1.0 — Synthetic oil 14B 1.0 0.0 2MPt: 0.5 TMHx: 0.5 Synthetic oil 15B 1.0 0.0 2EBu: 0.75 TMHx: 0.25 Synthetic oil 16B 0.0 1.0 2MBu: 0.5 2EHx: 0.5 Synthetic oil 17B 0.0 1.0 2MBu: 0.7 2EHx: 0.35 Synthetic oil 18B 0.0 1.0 2MBu: 1.0 — Synthetic oil 19B 0.10 0.90 2MBu: 1.0 — Synthetic oil 20B 0.70 0.30 2MBu: 0.5 TMHx: 0.5 Synthetic oil 21B 0.50 0.50 2MBu: 0.5 TMHx: 0.5 Synthetic oil 22B 0.30 0.70 2MBu: 0.5 TMHx: 0.5 Synthetic oil 23B 0.0 1.0 2MBu: 0.9 TMHx: 0.1 Synthetic oil 24B 0.0 1.0 2MBu: 0.7 TMHx: 0.3 Synthetic oil 25B 0.0 1.0 2MBu: 0.5 TMHx: 0.5 Synthetic oil 26B 1.0 0.0 LPt: 0.5 2EHx: 0.5 Synthetic oil 27B 1.0 0.0 LPt: 0.75 TMHx: 0.25 Synthetic oil 28B 1.0 0.0 LPt: 0.5 TMHx: 0.5 Synthetic oil 29B 1.0 0.0 2MBu: 1.0 — Synthetic oil 30B 1.0 0.0 2MBu: 0.75 2EHx: 0.25 Synthetic oil 31B 1.0 0.0 2MBu: 0.5 2EHx: 0.5 Synthetic oil 32B 0.70 0.30 2MBu: 0.85 2EHx: 0.15 Synthetic oil 33B 1.0 0.0 2MBu: 0.75 TMHx: 0.25 Synthetic oil 34B 1.0 0.0 2MPt: 1.0 — Synthetic oil 35B 1.0 0.0 2MPt: 0.75 2EHx: 0.25 Comparative oil 1B 1.0 0.0 2EHx: 0.5 TMHx: 0.5 Comparative oil 2B 1.0 0.0 LHx: 0.25 TMHx: 0.75 Comparative oil 3B 0.0 1.0 LHx: 0.65 TMHx: 0.35 Comparative oil 4B 0.0 1.0 LHx: 1.0 — Comparative oil 5B 1.0 0.0 2EBu: 1.0 — Comparative oil 6B 0.65 0.35 2EHx: 1.0 — Comparative oil 7B 0.0 1.0 LHx: 0.35 TMHx: 0.65 Comparative oil 8B 1.0 0.0 TMHx: 1.0 — Comparative oil 9B 0.0 1.0 2EHx: 0.5 TMHx: 0.5 Comparative oil 10B 0.0 1.0 2MPt: 0.35 2EHx: 0.65 Comparative oil 11B 1.0 0.0 2EHx: 1.0 — Comparative oil 12B 1.0 0.0 LPt: 0.25 2EHx: 0.75 Comparative oil 13B 1.0 0.0 LHx: 0.5 TMHx: 0.5 Comparative oil 14B 1.0 0.0 2MPt: 0.25 2EHx: 0.75 Comparative oil 15B refrigerant R-290/mineral oil for air conditioner Comparative oil 16B complex ester obtained from PE, 2EHx, adipic acid, etc. Comparative oil 17B 0.8 0.2 LPt: 0.4 n-heptanoic acid: 0.4 TMHx: 0.2 Comparative oil 18B mixed oil (refrigeration oil B, 25 wt % + comparative oil 1, 75 wt %) Makeup of refrigeration oil B Alcohol: neopentyl glycol Fatty acid: 2EHx Comparative oil 19B mixed oil (refrigeration oil B, 50 wt % + comparative oil 9, 50 wt %) Makeup of refrigeration oil B Alcohol: neopentyl glycol Fatty acid: 2EHx Comparative oil 20 mixed oil (refrigeration oil B, 30 wt % + comparative oil 16, 70 wt %) Makeup of refrigeration oil B Alcohol: neopentyl glycol Fatty acid: 2EHx

Test Example 1B With Respect to Kinematic Viscosities of Each Polyol Ester Oil Synthesized

Each of the polyol ester oils and comparative oils was examined for kinematic viscosity at 40° C. and 100° C. The results of the measurement are shown in Tables 47 and 48.

TABLE 47 Kinematic viscosity mm²/ mm²/ Example No. Oil No. s (40° C.) s (100° C.) Remarks Example 1B synthetic oil 1B 69.7 8.67 — Example 2B synthetic oil 2B 66.9 8.42 — Example 3B synthetic oil 3B 66.0 8.39 — Example 4B synthetic oil 4B 64.5 8.20 — Example 5B synthetic oil 5B 97.8 10.9 — Example 6B synthetic oil 6B 75.1 9.10 — Example 7B synthetic oil 7B 60.0 7.76 — Example 8B synthetic oil 8B 66.1 8.23 — Example 9B synthetic oil 9B 64.4 8.20 — Example 10B synthetic oil 10B 62.5 7.98 — Example 11B synthetic oil 11B 67.1 9.88 — Example 12B synthetic oil 12B 69.0 9.26 — Example 13B synthetic oil 13B 61.8 8.71 — Example 14B synthetic oil 14B 53.9 7.39 — Example 15B synthetic oil 15B 70.0 6.99 — Example 16B synthetic oil 16B 140 13.8 — Example 17B synthetic oil 17B 139 13.6 — Example 18B synthetic oil 18B 141 13.6 — Example 19B synthetic oil 19B 124 12.4 — Example 20B synthetic oil 20B 108 11.4 — Example 21B synthetic oil 21B 149 14.0 — Example 22B synthetic oil 22B 196 16.7 — Example 23B synthetic oil 23B 164 15.0 — Example 24B synthetic oil 24B 225 18.3 — Example 25B synthetic oil 25B 276 20.9 — Example 26B synthetic oil 26B 27.8 4.99 — Example 27B synthetic oil 27B 24.8 4.88 — Example 28B synthetic oil 28B 42.7 6.69 — Example 29B synthetic oil 29B 25.7 4.39 — Example 30B synthetic oil 30B 29.4 4.83 — Example 31B synthetic oil 31B 36.8 5.47 — Example 32B synthetic oil 32B 47.3 6.48 — Example 33B synthetic oil 33B 37.3 5.66 — Example 34B synthetic oil 34B 22.4 4.31 — Example 35B synthetic oil 35B 26.0 4.67 —

TABLE 48 Kinematic viscosity Comparative mm²/s Example No. Oil No. mm²/s (40° C.) (100° C.) Remarks Comparative comparative 67.8 8.34 — Example 1B oil 1B Comparative comparative 64.6 8.50 — Example 2B oil 2B Comparative comparative 88.0 11.9 — Example 3B oil 3B Comparative comparative 53.0 8.72 solidified at Example 4B oil 4B room temperature Comparative comparative 54.0 6.36 solidified at Example 5B oil 5B room temperature Comparative comparative 70.4 8.74 — Example 6B oil 6B Comparative comparative 181 17.6 — Example 7B oil 7B Comparative comparative 114 11.5 solidified at Example 8B oil 8B room temperature Comparative comparative 228 19.2 — Example 9B oil 9B Comparative comparative 116 12.9 — Example 10B oil 10B Comparative comparative 44.3 6.26 — Example 11B oil 11B Comparative comparative 34.1 5.44 — Example 12B oil 12B Comparative comparative 40.5 6.58 — Example 13B oil 13B Comparative comparative 36.4 5.60 — Example 14B oil 14B Comparative comparative 95.9 8.09 — Example 15B oil 15B Comparative comparative 226 21.8 — Example 16B oil 16B Comparative comparative 30.3 5.73 — Example 17B oil 17B Comparative comparative 33.8 5.44 — Example 18B oil 18B Comparative comparative 32.4 5.42 — Example 19B oil 19B Comparative comparative 67.4 9.42 — Example 20B oil 20B

Test 2B With Respect to Solubility with R-290 and Kinematic Viscosity

Each polyol ester oil and R-290 were enclosed in a glass tube so as to result in an oil content of 20% by weight, and the glass tube was shaken to dissolve the R-290 in the polyol ester oil. After the dissolution, the glass tube was placed in a water bath and gradually heated to measure the temperature at which the even layer separated into an oil layer and a refrigerant layer (high-temperature-side two-layer separation temperature). Meanwhile, the glass tube was placed in a cooling chamber and gradually cooled to measure the temperature at which the even layer separated into an oil layer and a refrigerant layer (low-temperature-side two-layer separation temperature). The results of the measurements and the kinematic viscosities are both shown in Table 49 to Table 51.

TABLE 49 Refrigerant R-290/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 36B synthetic oil 1B +70 or higher −50 or lower 69.7 Example 37B synthetic oil 2B +70 or higher −50 or lower 66.9 Example 38B synthetic oil 3B +70 or higher −50 or lower 66.0 Example 39B synthetic oil 4B +70 or higher −50 or lower 64.5 Example 40B synthetic oil 5B +70 or higher −50 or lower 97.8 Example 41B synthetic oil 6B +70 or higher −50 or lower 75.1 Example 42B synthetic oil 7B +70 or higher −50 or lower 60.0 Example 43B synthetic oil 8B +70 or higher −50 or lower 66.1 Example 44B synthetic oil 9B +70 or higher −50 or lower 64.4 Example 45B synthetic oil 10B +70 or higher −50 or lower 62.5 Example 46B synthetic oil 11B +70 or higher −50 or lower 67.1 Example 47B synthetic oil 12B +70 or higher −50 or lower 69.0 Example 48B synthetic oil 13B +70 or higher −50 or lower 61.8 Example 49B synthetic oil 14B +70 or higher −50 or lower 53.9 Example 50B synthetic oil 15B +70 or higher −50 or lower 70.0 Comparative comparative oil 4B +70 or higher −50 or lower 53.0 Example 21B solidified at room temperature Comparative comparative oil 5B +70 or higher −50 or lower 54.0 Example 22B solidified at room temperature

TABLE 50 Refrigerant R-290/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-350 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 51B synthetic oil 16B +70 or higher −50 or lower 140 Example 52B synthetic oil 17B +70 or higher −50 or lower 139 Example 53B synthetic oil 18B +70 or higher −50 or lower 141 Example 54B synthetic oil 19B +70 or higher −50 or lower 124 Example 55B synthetic oil 20B +70 or higher −50 or lower 108 Example 56B synthetic oil 21B +70 or higher −50 or lower 149 Example 57B synthetic oil 22B +70 or higher −50 or lower 196 Example 58B synthetic oil 23B +70 or higher −50 or lower 164 Example 59B synthetic oil 24B +70 or higher −50 or lower 225 Example 60B synthetic oil 25B +70 or higher −50 or lower 276 Comparative comparative oil 8B separated separated 114 Example 23B throughout throughout solidified the whole range the whole range at room temperature

TABLE 51 Refrigerant R-290/small refrigerated facility (as refrigeration oil having kinematic viscosity at 40° C. of 15-50 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 61B synthetic oil 26B +70 or higher −50 or lower 27.8 Example 62B synthetic oil 27B +70 or higher −50 or lower 24.8 Example 63B synthetic oil 28B +70 or higher −50 or lower 42.7 Example 64B synthetic oil 29B +70 or higher −50 or lower 25.7 Example 65B synthetic oil 30B +70 or higher −50 or lower 29.4 Example 66B synthetic oil 31B +70 or higher −50 or lower 36.8 Example 67B synthetic oil 32B +70 or higher −50 or lower 47.2 Example 68B synthetic oil 33B +70 or higher −50 or lower 37.3 Example 69B synthetic oil 34B +70 or higher −50 or lower 22.4 Example 70B synthetic oil 35B +70 or higher −50 or lower 26.0

Test Example 3B With Respect to Solubility with R-600a and Kinematic Viscosity

The high-temperature-side two-layer separation temperature and the low-temperature-side two-layer separation temperature were measured in the same manners as in Test Example 1B, except that R-600a was used as a hydrocarbon-based refrigerant. The results of the measurements and the kinematic viscosities are both shown in Table 52 and Table 53.

TABLE 52 Refrigerant R-600a/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 71B synthetic oil 1B +70 or higher −50 or lower 69.7 Example 72B synthetic oil 2B +70 or higher −50 or lower 66.9 Example 73B synthetic oil 3B +70 or higher −50 or lower 66.0 Example 74B synthetic oil 4B +70 or higher −50 or lower 64.5 Example 75B synthetic oil 5B +70 or higher −50 or lower 97.8 Example 76B synthetic oil 6B +70 or higher −50 or lower 75.1 Example 77B synthetic oil 7B +70 or higher −50 or lower 60.0 Example 78B synthetic oil 8B +70 or higher −50 or lower 66.1 Example 79B synthetic oil 9B +70 or higher −50 or lower 64.4 Example 80B synthetic oil 10B +70 or higher −50 or lower 62.5 Example 81B synthetic oil 11B +70 or higher −50 or lower 67.1 Example 82B synthetic oil 12B +70 or higher −50 or lower 69.0 Example 83B synthetic oil 13B +70 or higher −50 or lower 61.8 Example 84B synthetic oil 14B +70 or higher −50 or lower 53.9 Example 85B synthetic oil 15B +70 or higher −50 or lower 70.0 Comparative comparative oil 5B +70 or higher −50 or lower 54.0 Example 24B solidified at room temperature

TABLE 53 Refrigerant R-600a/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-350 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 86B synthetic oil 16B +70 or higher −50 or lower 140 Example 87B synthetic oil 17B +70 or higher −50 or lower 139 Example 88B synthetic oil 18B +70 or higher −50 or lower 141 Example 89B synthetic oil 19B +70 or higher −50 or lower 124 Example 90B synthetic oil 20B +70 or higher −50 or lower 108 Example 91B synthetic oil 21B +70 or higher −50 or lower 149 Example 92B synthetic oil 22B +70 or higher −50 or lower 196 Example 93B synthetic oil 23B +70 or higher −50 or lower 164 Example 94B synthetic oil 24B +70 or higher −50 or lower 225 Example 95B synthetic oil 25B +70 or higher −50 or lower 276 Comparative comparative oil 8B +70 or higher −50 or lower 114 Example 25B solidified at room temperature

Test Example 4B With Respect to Solubility with R-1270 and Kinematic Viscosity

The high-temperature-side two-layer separation temperature and the low-temperature-side two-layer separation temperature were measured in the same manners as in Test Example 1B, except that R-1270 was used as a hydrocarbon-based refrigerant. The results of the measurements and the kinematic viscosities are both shown in Table 54 to Table 56.

TABLE 54 Refrigerant R-1270/air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 96B synthetic oil 1B +70 or higher −50 or lower 69.7 Example 97B synthetic oil 2B +70 or higher −50 or lower 66.9 Example 98B synthetic oil 3B +70 or higher −50 or lower 66.0 Example 99B synthetic oil 4B +70 or higher −50 or lower 64.5 Example 100B synthetic oil 5B +70 or higher −50 or lower 97.8 Example 101B synthetic oil 6B +70 or higher −50 or lower 75.1 Example 102B synthetic oil 7B +70 or higher −50 or lower 60.0 Example 103B synthetic oil 8B +70 or higher −50 or lower 66.1 Example 104B synthetic oil 9B +70 or higher −50 or lower 64.4 Example 105B synthetic oil 10B +70 or higher −50 or lower 62.5 Example 106B synthetic oil 11B +70 or higher −50 or lower 67.1 Example 107B synthetic oil 12B +70 or higher −50 or lower 69.0 Example 108B synthetic oil 13B +70 or higher −50 or lower 61.8 Example 109B synthetic oil 14B +70 or higher −50 or lower 53.9 Example 110B synthetic oil 15B +70 or higher −50 or lower 70.0 Comparative comparative oil 4B +70 or higher −50 or lower 53.0 Example 26B solidified at room temperature Comparative comparative oil 5B +70 or higher −50 or lower 54.0 Example 27B solidified at room temperature

TABLE 55 Refrigerant R-1270/large refrigerated facility or air conditioner (as refrigeration oil having kinematic viscosity at 40° C. of 100-350 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 111B synthetic oil 16B +70 or higher −50 or lower 140 Example 112B synthetic oil 17B +70 or higher −50 or lower 139 Example 113B synthetic oil 18B +70 or higher −50 or lower 141 Example 114B synthetic oil 19B +70 or higher −50 or lower 124 Example 115B synthetic oil 20B +70 or higher −50 or lower 108 Example 116B synthetic oil 21B +70 or higher −50 or lower 149 Example 117B synthetic oil 22B +70 or higher −50 or lower 196 Example 118B synthetic oil 23B +70 or higher −50 or lower 164 Example 119B synthetic oil 24B +70 or higher −50 or lower 225 Example 120B synthetic oil 25B +70 or higher −50 or lower 276 Comparative comparative oil 8B separated separated 114 Example 28B throughout throughout solidified the whole range the whole range at room temperature

TABLE 56 Refrigerant R-1270/small refrigerated facility (as refrigeration oil having kinematic viscosity at 40° C. of 15-50 mm²/s) Properties High-temperature- Low-temperature- Example side two-layer side two-layer Kinematic Comparative separation separation viscosity Example temperature temperature (40° C.) No. Oil No. ° C. ° C. mm²/s Example 121B synthetic oil 26B +70 or higher −50 or lower 27.8 Example 122B synthetic oil 27B +70 or higher −50 or lower 24.8 Example 123B synthetic oil 28B +70 or higher −50 or lower 42.7 Example 124B synthetic oil 29B +70 or higher −50 or lower 25.7 Example 125B synthetic oil 30B +70 or higher −50 or lower 29.4 Example 126B synthetic oil 31B +70 or higher −50 or lower 36.8 Example 127B synthetic oil 32B +70 or higher −50 or lower 47.2 Example 128B synthetic oil 33B +70 or higher −50 or lower 37.3 Example 129B synthetic oil 34B +70 or higher −50 or lower 22.4 Example 130B synthetic oil 35B +70 or higher −50 or lower 26.0

Test Example 5B With Respect to Lubricity of Refrigeration Oils

Examples 1B, 2B, 3B, 4B, and 8B and Comparative Example 1B were evaluated with a Falex tester. The results thereof are shown in Table 57.

(Test Conditions)

Test apparatus: Falex tester (PIN-VEE BLOCK)

Test temperature: 80° C.

Test load: 150 lbs

Test period: 4 hr

Rotation speed: 290 rpm

TABLE 57 Example/Comparative Example No. Comparative Example Example Example Example Example Example 131B 132B 133B 134B 135B 29B Oil No. synthetic synthetic synthetic synthetic synthetic comparative oil 1B oil 2B oil 3B oil 4B oil 8B oil 1B 2EHx molar 1 0.5 0.32 0.15 0 0.52 ratio DiPE molar 0.34 0.44 0.46 0.45 0.5 0 ratio Average 766 700 670 632 615 668 molecular weight Wear ratio 0.61 0.92 0.63 0.98 0.51 1 (Relative value, with Comparative Example 1B taken as 1)

Test Example 6B With Respect to Hygroscopicity

Example 2B and Comparative Example 1B were evaluated through a hygroscopicity test. The results thereof are shown in Table 58.

(Test Conditions)

Test apparatus: A hygroscopicity tester based on a combination of a humidifier, acrylic case, turntable, fan, heater, hygrometer, and thermometer was produced and used.

Test temperature: 30° C.

Test humidity: 80% RH

Surface area of specimen: 21.2 cm²

TABLE 58 Comparative Example 136B/ Example 136B Example 30B Comparative Test Synthetic oil 2B Comparative oil 1B Example 30B period, moisture content, moisture content, Moisture hr ppm ppm content ratio 0 24 22 1.09 1 148 174 0.85 2 261 350 0.74 3 334 500 0.67 4 431 640 0.67 6 605 790 0.77 8 780 921 0.85 10 932 1030 0.90 15 1200 1180 1.02 26 1587 1336 1.19 48 2150 1459 1.47 72 2296 1580 1.52 96 2523 1622 1.55

The open time which was supposed when facility dealers handled refrigeration oils was set at 0.5 to 3 hours among the test periods shown in Table 58, and refrigeration oils were compared in the degree of moisture absorption in a range including shorter and longer periods. The results thereof are shown in FIG. 2.

Test Example 7B With Respect to Hydrolytic Resistance

A polyol ester oil which had a moisture content of 500 ppm and to which an antioxidant and an acid scavenger had been added as additives was enclosed in a glass tube together with refrigerant R-290 and an iron wire, copper wire, or aluminum wire as a catalyst, and a heating test was conducted for 14 days in a 175° C. thermostatic chamber. After completion of the heating period, the contents were examined for appearance, color, any change in the catalyst, and precipitate. Furthermore, the polyol ester oil which had undergone the test was taken out and examined for acid value. The results thereof are shown in Table 59 and Table 60.

TABLE 59 Example/Comparative Example No. Example Example Example Example Example Example 137B 138B 139B 140B 141B 142B Oil No. synthetic synthetic synthetic synthetic synthetic synthetic oil 1B oil 2B oil 3B oil 4B oil 5B oil 6B Appearance transparent transparent transparent transparent transparent transparent Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Change of catalyst, light light light light light light iron brown brown brown brown brown brown Change of catalyst, no no no no no no copper change change change change change change Change of catalyst, no no no no no no aluminum change change change change change change Precipitate none none none none none none Acid value, 0.04 0.04 0.04 0.05 0.04 0.04 mg-KOH/g

TABLE 60 Example/Comparative Example No. Comparative Comparative Example Example Example Example Example Example 143B 144B 145B 146B 31B 32B Oil No. synthetic synthetic synthetic synthetic comparative comparative oil 7B oil 8B oil 9B oil 10B oil 1B oil 15B Appearance transparent transparent transparent transparent transparent transparent Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Change of catalyst, light light light light light light iron brown brown brown brown brown brown Change of catalyst, no no no no no no copper change change change change change change Change of catalyst, no no no no no no aluminum change change change change change change Precipitate none none none none none none Acid value, 0.04 0.04 0.04 0.05 0.04 0.01 mg-KOH/g

Test Example 8B With Respect to Other Properties

Density, color, flash point, pour point, kinematic viscosity, viscosity index, and total acid number, as properties required of refrigeration oils, are shown in Table 61 to Table 65 on the basis of Examples and Comparative Examples.

TABLE 61 (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Example/Comparative Example No. Example Example Example Example Example 147B 148B 149B 150B 151B Oil No. synthetic synthetic synthetic synthetic synthetic oil 1B oil 2B oil 3B oil 4B oil 5B Density, 15° C. 0.99 1.00 1.01 1.02 1.00 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −35 −37.5 −40 −42.5 −35 Kinematic viscosity, 40° C. 69.7 66.9 66.0 62.5 97.8 mm²/s Kinematic viscosity, 100° C. 8.67 8.42 8.39 8.02 10.9 mm²/s Viscosity index 95 94 95 93 96 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g

TABLE 62 (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Example/Comparative Example No. Example Example Example Example Example 152B 153B 154B 155B 156B Oil No. synthetic synthetic synthetic synthetic synthetic oil 6B oil 7B oil 8B oil 9B oil 10B Density, 15° C. 1.02 0.98 1.03 0.97 1.00 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −35 −40 −37.5 −40 −35 Kinematic viscosity, 40° C. 75.1 60.0 66.1 64.4 62.5 mm²/s Kinematic viscosity, 100° C. 9.10 7.75 8.23 8.20 8.34 mm²/s Viscosity index 94 91 91 91 94 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g

TABLE 63 (as refrigeration oil having kinematic viscosity at 40° C. of 50-100 mm²/s) Example/Comparative Example No. Example Example Example Example Comparative 157B 158B 159B 160B Example 33B Oil No. synthetic synthetic synthetic synthetic comparative oil 11B oil 12B oil 13B oil 15B oil 1B Density, 15° C. 1.03 1.01 0.98 1.03 0.959 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −47.5 −42.5 −42.5 −35 −40 Kinematic viscosity, 40° C. 67.1 69.0 61.8 70.0 67.8 mm²/s Kinematic viscosity, 100° C. 9.88 9.26 8.71 6.99 8.34 mm²/s Viscosity index 130 111 115 61 90 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g

TABLE 64 (as refrigeration oil having kinematic viscosity at 40° C. of 100-320 mm²/s) Example/Comparative Example No. Example Example Example Example Comparative 161B 162B 163B 164B Example 34B Oil No. synthetic synthetic synthetic synthetic comparative oil 16B oil 17B oil 24B oil 25B oil 16B Density, 15° C. 1.01 1.02 1.00 0.99 1.02 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 224 Pour point, ° C. −35 −37.5 −35 −35 −32.5 Kinematic viscosity, 40° C. 140 139 225 276 226 mm²/s Kinematic viscosity, 100° C. 13.8 13.6 18.3 20.9 21.8 mm²/s Viscosity index 94 93 89 89 116 Moisture content, ppm 25 25 25 25 25 Total acid number, 0.01 0.01 0.01 0.01 0.01 mg-KOH/g

TABLE 65 (as refrigeration oil having kinematic viscosity at 40° C. of 15-50 mm²/s) Example/Comparative Example No. Example Example Example Example Comparative 165B 166B 167B 168B Example 35B Oil No. synthetic synthetic synthetic synthetic comparative oil 30B oil 31B oil 32B oil 35B oil 17B Density, 15° C. 1.00 0.99 1.02 0.99 0.99 g/cm³ Color (ASTM) L 0.5 L 0.5 L 0.5 L 0.5 L 0.5 Flash point, COC, ° C. 250 or higher 250 or higher 250 or higher 250 or higher 250 or higher Pour point, ° C. −42.5 −40 −42.5 −45 −50 Kinematic viscosity, 40° C. 29.4 36.8 47.3 26.0 30.3 mm²/s Kinematic viscosity, 100° C. 4.83 5.47 6.48 4.67 5.73 mm²/s Viscosity index 76 76 82 93 133 Moisture content, ppm 25 25 25 25 50 Total acid number, 0.01 0.01 0.01 0.01 0.02 mg-KOH/g

(List of Polyol Ester Oils for Each Raw Material Combination)

The Examples and the Comparative Examples are arranged with respect to each of raw material combinations to show that various viscosities and solubility with various refrigerants are obtained by changing the ratio of raw materials. The relationships between the raw material combination and kinematic viscosity or refrigerated facilities/air conditioners to which the oil is applicable are as shown in the following Table 66 to Table 75.

TABLE 66 Raw material combination (1): alcohols, PE and DiPE; acid 1, 2MBu; acid 2, 2EHx Kinematic viscosity Refrigerating Oil No. PE DiPE 2MBu 2EHx (40° C.) mm²/s apparatus Synthetic 0.60 0.40 0.4 0.6 69.7 air conditioner oil 1B Synthetic 0.55 0.45 0.5 0.5 66.9 air conditioner oil 2B Synthetic 0.55 0.45 0.7 0.3 66.0 air conditioner oil 3B Synthetic 0.55 0.45 0.85 0.15 64.5 air conditioner oil 4B Synthetic 0.30 0.70 0.5 0.5 97.8 air conditioner oil 5B Synthetic 0.55 0.45 0.45 0.55 75.1 air conditioner oil 6B Synthetic 0.0 1.0 0.5 0.5 140 large refrigerated facility oil 16B or air conditioner Synthetic 0.0 1.0 0.7 0.3 139 large refrigerated facility oil 17B or air conditioner Synthetic 0.0 1.0 1.0 0.0 141 large refrigerated facility oil 18B or air conditioner Synthetic 0.10 0.90 1.0 0.0 124 large refrigerated facility oil 19B or air conditioner Synthetic 1.0 0.0 1.0 0.0 25.7 small refrigerated facility oil 29B Synthetic 1.0 0.0 0.75 0.25 29.4 small refrigerated facility oil 30B Synthetic 1.0 0.0 0.5 0.5 36.8 small refrigerated facility oil 31B Synthetic 0.70 0.30 0.85 0.15 47.2 small refrigerated facility oil 32B Comparative 0.65 0.35 0.0 1.0 70.4 — oil 6B Comparative 1.0 0.0 0.0 1.0 44.3 — oil 11B

TABLE 67 Raw material combination (2): alcohols, PE and DiPE; acid 1, 2MBu; acid 2, TMHx Kinematic viscosity Refrigerating Oil No. PE DiPE 2MBu TMHx (40° C.) mm²/s apparatus Synthetic 1.0 0.0 0.5 0.5 60.0 air conditioner oil 7B Synthetic 0.50 0.50 1.0 0.0 66.1 air conditioner oil 8B Synthetic 1.0 0.0 0.4 0.6 64.4 air conditioner oil 9B Synthetic 0.85 0.15 0.6 0.4 62.5 air conditioner oil 10B Synthetic 0.0 1.0 1.0 0.0 141 large refrigerated facility oil 18B or air conditioner Synthetic 0.10 0.90 1.0 0.0 124 large refrigerated facility oil 19B or air conditioner Synthetic 0.70 0.30 0.5 0.5 108 large refrigerated facility oil 20B or air conditioner Synthetic 0.50 0.50 0.5 0.5 149 large refrigerated facility oil 21B or air conditioner Synthetic 0.30 0.70 0.5 0.5 196 large refrigerated facility oil 22B or air conditioner Synthetic 0.0 1.0 0.9 0.1 164 large refrigerated facility oil 23B or air conditioner Synthetic 0.0 1.0 0.7 0.3 225 large refrigerated facility oil 24B or air conditioner Synthetic 0.0 1.0 0.5 0.5 276 large refrigerated facility oil 25B or air conditioner Synthetic 1.0 0.0 1.0 0.0 25.7 small refrigerated facility oil 29B Synthetic 1.0 0.0 0.75 0.25 37.3 small refrigerated facility oil 33B Comparative 1.0 0.0 0.0 1.0 114 — oil 8B solidified at room temperature

TABLE 68 Raw material combination (3): alcohols, PE and DiPE; acid 1, LPt; acid 2, 2EHx Kinematic viscosity Refrigerating Oil No. PE DiPE LPt 2EHx (40° C.) mm²/s apparatus Synthetic 1.0 0.0 0.5 0.5 27.8 small oil 26B refrigerated facility Comparative 0.65 0.35 0.0 1.0 70.4 — oil 6B Comparative 1.0 0.0 0.0 1.0 44.3 — oil 11B Comparative 1.0 0.0 0.25 0.75 34.1 — oil 12B

TABLE 69 Raw material combination (4): alcohols, PE and DiPE; acid 1, LPt; acid 2, TMHx Kinematic viscosity Refrigerating Oil No. PE DiPE LPt TMHx (40° C.) mm²/s apparatus Synthetic oil 0.0 1.0 0.8 0.2 67.1 air 11B conditioner Synthetic 1.0 0.0 0.75 0.25 24.8 small oil 27B refrigerated facility Synthetic 1.0 0.0 0.5 0.5 42.7 small oil 28B refrigerated facility Comparative 1.0 0.0 0.0 1.0 114 — oil 8B solidified at room temperature

TABLE 70 Raw material combination (5): alcohols, PE and DiPE; acid 1, 2MPt; acid 2, 2EHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2MPt 2EHx mm²/s apparatus Synthetic 0.25 0.75 0.8 0.2 69.0 air conditioner oil 12B Synthetic 0.25 0.75 1.0 0.0 61.8 air conditioner oil 13B Synthetic 1.0 0.0 1.0 0.0 22.4 small refrigerated oil 34B facility Synthetic 1.0 0.0 0.75 0.25 26.0 small refrigerated oil 35B facility Comparative 0.65 0.35 0.0 1.0 70.4 — oil 6B Comparative 0.0 1.0 0.3 0.7 116 — oil 10B Comparative 1.0 0.0 0.0 1.0 44.3 — oil 11B Comparative 1.0 0.0 0.25 0.75 36.4 — oil 14B

TABLE 71 Raw material combination (6): alcohols, PE and DiPE; acid 1, 2MPt; acid 2, TMHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2MPt TMHx mm²/s apparatus Synthetic 0.25 0.75 1.0 0.0 61.8 air oil 13B conditioner Synthetic 1.0 0.0 0.5 0.5 53.9 air oil 14B conditioner Synthetic 1.0 0.0 1.0 0.0 22.4 small oil 34B refrigerated facility Comparative 1.0 0.0 0.0 1.0 114 — oil 8B solidified at room temperature

TABLE 72 Raw material combination (7): alcohols, PE and DiPE; acid 1, 2EBu; acid 2, TMHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2EBu TMHx mm²/s apparatus Synthetic 1.0 0.0 0.75 0.25 70.0 air conditioner oil 15B Comparative 1.0 0.0 0.0 1.0 114 — oil 8B solidified at room temperature

TABLE 73 Raw material combination (8): alcohols, PE and DiPE; acid 1, LHx; acid 2, TMHx Kinematic viscosity Refrigerating Oil No. PE DiPE LHx TMHx (40° C.) mm²/s apparatus Comparative 1.0 0.0 0.25 0.75 64.6 — oil 2B Comparative 0.0 1.0 0.67 0.33 88.0 — oil 3B Comparative 0.0 1.0 1.0 0.0 53.0 — oil 4B solidified at room temperature Comparative 0.0 1.0 0.3 0.7 181 — oil 7B Comparative 1.0 0.0 0.0 1.0 114 — oil 8B solidified at room temperature Comparative 1.0 0.0 0.5 0.5 40.5 — oil 13B

TABLE 74 Raw material combination (9): alcohols, PE and DiPE; acid 1, 2EHx; acid 2, TMHx Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE 2EHx TMHx mm²/s apparatus Comparative 1.0 0.0 0.5 0.5 67.8 air oil 1B conditioner Comparative 0.65 0.35 1.0 0.0 70.4 — oil 6B Comparative 1.0 0.0 0.0 1.0 114 — oil 8B solidified at room temperature Comparative 0.0 1.0 0.5 0.5 228 — oil 9B Comparative 1.0 0.0 1.0 0.0 44.3 — oil 11B

TABLE 75 Other combinations Kinematic viscosity (40° C.) Refrigerating Oil No. PE DiPE Acids mm²/s apparatus Comparative 0.8 0.2 LPt: 0.4 30.3 small oil 17B n-heptanoic refrigerated acid: 0.4 facility MHx: 0.2 Comparative refrigerant R-290/mineral oil 95.9 air oil 15B for air conditioner conditioner Comparative complex ester obtained 226 large oil 16B from PE, 2EHx, adipic refrigerated acid, etc. facility or air conditioner Refrigerating Alcohol: neopentyl glycol 7.56 domestic machine Fatty acid: 2EHx refrigerator oil B

The relationship between each raw material combination and the solubility with each refrigerant (low-temperature-side two-layer separation temperature) is as shown in the following Table 76 to Table 85.

TABLE 76 Alcohols, PE and DiPE; acid 1, 2MBu; acid 2, 2EHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2MBu 2EHx R-290 R-600a R-1270 Synthetic 0.60 0.40 0.4 0.6 −50 or lower −50 or lower −50 or lower oil 1B Synthetic 0.55 0.45 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 2B Synthetic 0.55 0.45 0.7 0.3 −50 or lower −50 or lower −50 or lower oil 3B Synthetic 0.55 0.45 0.85 0.15 −50 or lower −50 or lower −50 or lower oil 4B Synthetic 0.30 0.70 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 5B Synthetic 0.55 0.45 0.45 0.55 −50 or lower −50 or lower −50 or lower oil 6B Synthetic 0.0 1.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 16B Synthetic 0.0 1.0 0.7 0.3 −50 or lower −50 or lower −50 or lower oil 17B Synthetic 0.0 1.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 18B Synthetic 0.10 0.90 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 19B Synthetic 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 29B Synthetic 1.0 0.0 0.75 0.25 −50 or lower −50 or lower −50 or lower oil 30B Synthetic 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 31B Synthetic 0.70 0.30 0.85 0.15 −50 or lower −50 or lower −50 or lower oil 32B Comparative 0.65 0.35 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 6B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 11B

TABLE 77 Alcohols, PE and DiPE; acid 1, 2MBu; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2MBu TMHx R-290 R-600a R-1270 Synthetic 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 7B Synthetic 0.50 0.50 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 8B Synthetic 1.0 0.0 0.4 0.6 −50 or lower −50 or lower −50 or lower oil 9B Synthetic 0.85 0.15 0.6 0.4 −50 or lower −50 or lower −50 or lower oil 10B Synthetic 0.0 1.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 18B Synthetic 0.10 0.90 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 19B Synthetic 0.70 0.30 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 20B Synthetic 0.50 0.50 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 21B Synthetic 0.30 0.70 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 22B Synthetic 0.0 1.0 0.9 0.1 −50 or lower −50 or lower −50 or lower oil 23B Synthetic 0.0 1.0 0.7 0.3 −50 or lower −50 or lower −50 or lower oil 24B Synthetic 0.0 1.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 25B Synthetic 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 29B Synthetic 1.0 0.0 0.75 0.25 −50 or lower −50 or lower −50 or lower oil 33B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 8B

TABLE 78 Alcohols, PE and DiPE; acid 1, LPt; acid 2, 2EHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE LPt 2EHx R-290 R-600a R-1270 Synthetic 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 26B Comparative 0.65 0.35 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 6B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 11B Comparative 1.0 0.0 0.25 0.75 −50 or lower −50 or lower −50 or lower oil 12B

TABLE 79 Alcohols, PE and DiPE; acid 1, LPt; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE LPt TMHx R-290 R-600a R-1270 Synthetic 0.0 1.0 0.8 0.2 −50 or lower −50 or lower −50 or lower oil 11B Synthetic 1.0 0.0 0.75 0.25 −50 or lower −50 or lower −50 or lower oil 27B Synthetic 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 28B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 8B

TABLE 80 Alcohols, PE and DiPE; acid 1, 2MPt; acid 2, 2EHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2MPt 2EHx R-290 R-600a R-1270 Synthetic 0.25 0.75 0.8 0.2 −50 or lower −50 or lower −50 or lower oil 12B Synthetic 0.25 0.75 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 13B Synthetic 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 34B Synthetic 1.0 0.0 0.75 0.25 −50 or lower −50 or lower −50 or lower oil 35B Comparative 0.65 0.35 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 6B Comparative 0.0 1.0 0.3 0.7 −50 or lower −50 or lower −50 or lower oil 10B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 11B Comparative 1.0 0.0 0.25 0.75 +32 −19 −50 or lower oil 14B

TABLE 81 Alcohols, PE and DiPE; acid 1, 2MPt; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2MPt 2EHx R-290 R-600a R-1270 Synthetic 0.25 0.75 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 13B Synthetic 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 14B Synthetic 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 34B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 8B

TABLE 82 Alcohols, PE and DiPE; acid 1, 2EBu; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2EBu TMHx R-290 R-600a R-1270 Synthetic 1.0 0.0 0.75 0.25 −50 or lower −50 or lower −50 or lower oil 15B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 8B

TABLE 83 Alcohols, PE and DiPE; acid 1, LHx; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE LHx TMHx R-290 R-600a R-1270 Comparative 1.0 0.0 0.25 0.75 −50 or lower −50 or lower −50 or lower oil 2B Comparative 0.0 1.0 0.67 0.33 −50 or lower −50 or lower −50 or lower oil 3B Comparative 0.0 1.0 0.3 0.7 −50 or lower −50 or lower −50 or lower oil 7B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 8A Comparative 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 13B

TABLE 84 Alcohols, PE and DiPE; acid 1, 2EHx; acid 2, TMHx Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE 2EHx TMHx R-290 R-600a R-1270 Comparative 1.0 0.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 1B Comparative 0.65 0.35 1.0 0.0 −50 or lower −50 or lower −50 or lower oil 6B Comparative 1.0 0.0 0.0 1.0 −50 or lower −50 or lower −50 or lower oil 8B Comparative 0.0 1.0 0.5 0.5 −50 or lower −50 or lower −50 or lower oil 9B Comparative 1.0 0.0 1.0 0.0 −50 or lower −50 or lower −50 or less oil 11B

TABLE 85 Other combinations Low-temperature-side two-layer separation temperature (oil content, 20%), ° C. Oil No. PE DiPE Acids R-290 R-600a R-1270 Comparative 0.8 0.2 LPt: 0.4 −50 or lower −50 or lower −50 or lower oil 17B n-heptanoic acid: 0.4 TMHx: 0.2 Comparative refrigerant R-290/mineral oil −50 or lower −50 or lower −50 or lower oil 15B for air conditioner Comparative complex ester obtained from −50 or lower −50 or lower −50 or lower oil 16B PE, 2EHx, adipic acid, etc. Refrigerating Alcohol: neopentyl glycol −50 or lower −50 or lower −50 or lower machine Fatty acid: 2EHx oil B

As shown in Table 66 to Table 75, the polyol ester oils each produced by esterifying an alcohol ingredient obtained by mixing pentaerythritol with dipentaerythritol and a fatty acid ingredient composed of at least one of pentanoic acid and hexanoic acid and at least one of octanoic acid and nonanoic acid are made to have various values of viscosity by changing the proportions of the raw materials with respect to each of specific raw material combinations.

Furthermore, as shown in Table 49 to Table 56, refrigeration oil compositions which are excellent in terms of solubility and lubricity can be produced even with hydrocarbon refrigerants having an exceedingly low global warming potential, by using polyol ester oils each produced by esterifying an alcohol ingredient obtained by mixing pentaerythritol with dipentaerythritol and a fatty acid ingredient composed of at least one of pentanoic acid and hexanoic acid and at least one of octanoic acid and nonanoic acid.

Moreover, as shown in Table 61 to Table 65, the polyol ester oils each produced by esterifying an alcohol ingredient obtained by mixing pentaerythritol with dipentaerythritol and a fatty acid ingredient composed of at least one of pentanoic acid and hexanoic acid and at least one of octanoic acid and nonanoic acid have the properties and performances which are required of refrigeration oils, as compared with the mineral oil (comparative oil 15B) for refrigerant R290 and with Comparative Example 1B, etc.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

This application is based on a Japanese patent application filed on Dec. 27, 2011 (Application No. 2011-286045) and a Japanese patent application filed on Dec. 12, 2012 (Application No. 2012-270435), the contents thereof being incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The present invention is useful as refrigeration oil compositions for hydrofluorocarbon-based refrigerants or hydrocarbon-based refrigerants. 

1. A refrigeration oil composition containing a polyol ester oil which is soluble with either a hydrofluorocarbon-based refrigerant or a hydrocarbon-based refrigerant, wherein the polyol ester oil is a product of the esterification of an alcohol ingredient containing pentaerythritol and dipentaerythritol and a fatty acid ingredient containing at least one of a linear or branched fatty acid having 5 carbon atoms and a linear or branched fatty acid having 6 carbon atoms and containing at least one of a linear or branched fatty acid having 8 carbon atoms and a linear or branched fatty acid having 9 carbon atoms, at least one of the linear or branched fatty acid having 5 carbon atoms and linear or branched fatty acid having 6 carbon atoms in the fatty acid ingredient accounts for 20 to 100% by mol of the total amount of the fatty acid ingredient, and either the alcohol ingredient or the fatty acid ingredient is a mixture composed of two components.
 2. The refrigeration oil composition according to claim 1, wherein at least one of the fatty acids which constitute the fatty acid ingredient is a branched fatty acid.
 3. The refrigeration oil composition according to claim 1, wherein the fatty acid ingredient is a mixture of: at least one of 2-methylbutanoic acid and 2-methylpentanoic acid; and at least one of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid.
 4. The refrigeration oil composition according to claim 1, wherein the fatty acid ingredient is a mixture of 2-methylbutanoic acid and 2-ethylhexanoic acid.
 5. The refrigeration oil composition according to claim 1, wherein the hydrofluorocarbon-based refrigerant comprises at least one member selected from R-32, R-410A, HFO-1234yf, and HFO-1234ze(E).
 6. The refrigeration oil composition according to claim 1, wherein the hydrocarbon-based refrigerant comprises at least one member selected from R-290, R-600a, and R-1270.
 7. The refrigeration oil composition according to claim 1, having a low-temperature-side two-layer separation temperature and a high-temperature-side two-layer separation temperature, with respect to separation from the hydrofluorocarbon-based refrigerant or hydrocarbon-based refrigerant as measured at an oil content of 20% by weight, of +20 degrees or lower and +35 degrees or higher, respectively.
 8. The refrigeration oil composition according to claim 1, containing at least one of an antioxidant, an epoxy-compound acid scavenger, and an extreme-pressure agent. 